This is what I gather, please correct any mistake. I will edit the post with updated info. I have not included information from many posters who have insufficient contextual information with their posted resuts.

============================================
Chipset: Ali Interface: USB 2.0

Tester: qwakrz
Best Firmware version: 47L9 for official BenQ external model EW1621
Compatibility w/best FW: 12x or greater DVD R burning , CDR/W burning
Flashability through USB: Unknown
Notes: Internal drive(DW1620) firmwares will work for DVD burning but will not burn CDR/W's

===========================================
Chipset: Prolific 3507 Interface: USB 2.0, Firewire(IEEE 1394)

Main Tester: dishinit
Best Firmware Version: 47L9 for official BenQ external model EW1621 with updated prolific
Compatibilty w/best FW: 12x DVDR/W USB, 12x DVDR/WFirewire, CDR/W unknown
Note: Besides the DVD Writer drive, you should upgrade the Prolific Firmware through the USB interface.
===========================================
Chipset: Oxford 911 Interface: Firewire (IEEE 1394)

Testers: krkdnose, eleewhm
Best tested Firmware version: B7P9
Compatibility: SLOW(not even 12x) but works for DVD writing

============================================
Chipset: Cypress AT2 Interface: USB 2.0

Tester: krymson
Best Firmware: ???
Compatibility: Does not work with tested firmware G7M9, B7K9, B7P9

=============================================
Conclusion

Best chipset from what I gather seems to be the updated Prolific chipset, with a 47L9 EW1601 firmware update, which requires the 47L9 CVT file and a CVT flash utility, either windwflash.exe or the dos flasher DVDFlash.exe .All these are available at
http://dvdpro.club.st/firmware/BENQ_FW.htm

There is one caveat: I have heard the Prolific chipset may have problems with Hard disks. This may be just a rumor.

Can I just add to that list,

My current setup is:

Firmware : B7S9
Enclosure : USB2 / Prolific FireWire
Flashability : USB2 OK, FireWire 90% ok (occasional failure & reflash to fix)
Max Speed (PC Chipset dependant) 12x DVD, error reported on the speed of reading, reports higher read speed than it is actually doing.

No problems with this case, works with all media I throw at it but is limited to 12x by the chipset on my Mobo / bridge chipset. Have not fully tried it at 16x as my media does not handle high speed well.

http://specialtech.co.uk/spshop/cust...?productid=641

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As a side note, the speeds that can be obtained seem to be more relyant on the speed of the host controller chipset more than the bridge chip that is used but it does have some effect.

Thanks for the info

I got my external enclosure today and it didn't work. I'll post the info as soon is I found out what chipset it uses (was a cheap one)

Ha, seems like you can only edit post for a limited amount of time.
2qwakrz: I was going to post that firewire updating was possible but dishinit posted that his update wasn't 100%.

Chipset: Cypress AT2 Interface: USB 2.0

Tester: krymson
Best Firmware: none known
Compatibility: Does not work with firmware G7M9, B7K9, B7P9 , A7L9

Firmware updates should be performed over direct IDE. That means stick it inside a desktop computer and flash it there. The ability to flash update as mentioned by qwakrz with prolific firewire seems to be the exception and not the rule.

You can find chipset information on most popular external enclosures at Dealsonic's External Enclosure Section . They have pretty good prices too

krymson,

I've had 100% success upgrading, crossflashing (WinDWflash + cvt files) & backflashing on my BenQ-OEM 1620, B7S9>B7P9, via "USB 2".
qwakrz also confirmed this in above post.
Not so successful on Firewire.
Thought Laptop users would appreciate this info.
dishinit

Excuse me, I forgot to add that this was using a Prolific 3507 chipset upgraded to Sept 7, 2004 firmware.
My two Prolific chipset cases are from:
ArrowMicro (Newegg)
Plumax (Dealsonic)
Confirm Prolific chipset befor purchase.

I found a very intersting problem.
Chipset: Oxford 922 FW800 Chipset
Benq 1620 @ B7P9 as Master, Pioneer 108A @ >NIL 1.14 as slave.
Software DVDDecrypter (no nero or other CDR/DVD burning software installed), using SPTI interface.
When I try buring an ISO image using the latest version of DVDDecrypter 3.5.1.0, it is reported that BENQ 1620 can burn up to 30X!!!!
The whole image takes about 2 minutes to burn... and you guess it, it is not a valid disc..... in fact, I can't get the drive to response after the burning starts.... After rebooting the enclosure and take out the disc, it looks as if the disc is not burnt at all.... However, some marking is probably written that the disc is no longer 'empty'....
Seems that BENQ's firmware isn't very enclosure friendly....
Same image burns fine with DVD Decrypter on the Pioneer 108.... go figure....
It is using the latest firmware already.... I belive...

dishinit ,

Which model of the ArrowMicro at Newegg are you using-FW/US2 combo or just one of the interfaces.

thanks

jrsds,
I use both connections, USB & Firewire, but just one at a time (either USB or Firewire) depending upon which computer my external cases are connected to.
As the BenQ 1620 cannot write/burn faster than 12X over either Firewire or USB (unlike the NEC 3500), I am prone to connect the USB innerface as there seems to be no atvantage using Firewire on an optical drive.
When using a USB innerface, I can also cross flash BenQ firmware, should I so desire, with no problems.
However, I did experience BenQ firmware flash failure when using Firewire innerface (I was more than a little freaked, new drive and all, do I did not try USB at that time). I recovered by IDE channel re-flash.
I seem to get identical scans from my internal BenQ and my external BenQ on USB, and I burn actively from both units.
What I do see, is there is a degree of variation/quality, from one blank disc to another in the same spindle. This has been especially true for CMC MAG E01, and somewhat less true for Ty, Ritek, Ricoh & MCC.
I QScan each disc before I burn. This variation between disc's is confirmed by scanning on either BenQ (internal---external), same results. I prefer quality burns over speed.

Just one note of caution, about the Prolific chipset, there appears to be delayed write problems when using this chipset (regardless of Sept firmware upgrade) when using case with a hard drive larger than 80 GB.
Do a search on Prolific 3507 and you will garner more info.
Keep in mind when getting an external case, There seems to be no "right" or "all in one" solution to the external case & chipset issue yet.
Hope this helps.
dishinit

I have my oem 1620 (flashed to retail) in a Macally external case model PHC-500BC, it is USB 2.0 and FW using Initio chipset ver. 4.70

I do not have USB 2.0 on my laptop so I've only used the FW interface.

The facts:

I can update the enclosure firmware via FW

I can update th BenQ 1620 firmware via FW

My burst rate is 19 MB/s, just short of 16x capable but enough for 12x

I burn with Nero 6.6.0.1 using Verbatim 8x media MCC03 @ 12x

After 25 burns my fastest full disk burn was 6:28 and I'm averaging around 6:32

My best quality score in CD Speed 3.55 is 97, the worst 94, avg 96

Like most I am disappointed in not getting 16x speed but I'm more than pleased with the quality. Its only like 30 seconds slower anyway and I'll trade that for the portability.

jrsds,
Just realized that my post did not answer your original question "Which model "
ArrowMicro = PM-525C2-PPS
Plumax = PM-525C2-PPB

toofnevil,
Appreciate your post, clear & informative.
Good to hear no problems updating via Firewire on your Macally external case with Initio chipset ver. 4.70.
After my "firmware flash failed" message via firewire, I am hesitant to try again using 1394 interface..
I have just cross flashed my external 1620, B7P9 (via USB 2) to EW1621, 47L9 to run some burn test. Currently burning a Yuden T02 at 12X.
As I have several brands of media, both +R & -R, both quality & questionable....my Disc Quality scores (depending on media code) range from 68 (CMC MAG E01) to 99 (MCC 003). I am not sure if switching from one media to another effects quality burns.
I usually burn 3 to 4 of the same media at a time, unless, I get a 68 score (which is entirely playable on my Stand alone DVD player) and want higher disc quality for the burn.
My burst rates are:
19MB/s = USB 2
21MB/s = Firewire
23MB/s when on internal IDE

With 21MB/s on Firewire, I am still limited to 12X burns. With 23MB/s internal IDE, I can burn at 16X.
dishinit