To answer your question............

Here, try something real simple.
Use Opera or even Firefox to download any firmware from this page......
http://www.liteonit.com/ODD/English/...e_dvd%20rw.asp

For some reason I can't.
But I have absolutely no problems with Internet Explorer.

I hope this example answers your question. If not I have many more examples why these beta browsers cannot be my main browser.

And oh, try this security test that Internet Explorer passed with flying colors.

Multiple Browsers IDN Spoofing Test

Opera has been aware of this since version 7.54 and still they have no fix. I'm running Opera v8.02 build 7680 and still this has not been fixed. At least Microsoft tend to their exposed security flaws. And by the way, I AM NOT A MICROSOFT FAN!!!!!
Opera IDN Spoofing Security Issue

There are no browsers without security flaws, and this certainly includes Opera and Firefox. These are just not exploited as much since they are only minority beta browsers.