well, I've just tried the last version with Wavgain as you pointed, and there are still gaps...

The 1st image below has a gap more than 1000 samples long (2 sectors / 30 mseconds). It's not very easily perceived but I can hear it...
Probably Foobar2k can do a better job...

The 2nd image shows the same zone for Feurio! without editing anything.
The gap is slightly shorter than with burnatonce but it's still there.
You still have to manually remove it if you want nice discs.