I didn't find bugs in the stable version because it is stable and I have it installed. Maybe you remember I was among the 1st ones to try out the beta too.
For me it's timing-related problem instead of beta/final testing problem: I can only work on QC extensively during weekends and everything then takes forever. Even now I don't have a full 3.0 e-shop working, there is still some stuff to do. And as I work with it, and on it, I find bugs. It's normal that I find bugs in final version, a normal development process.
BTW, I guess the related problem is this: not enough people test beta or other latest versions, because they still use old versions and they also receive support for them. Once you cut the support for 2.x and 1.x, you would see many people surging toward 3.0 (if they knew that they would receive the full support there). Make ONLY the latest version fully supported and there will be even more bugs found, since I reckon more users = more thorough testing.
And then when you release a new 3.1 version, just include a list of files that were changed from 3.0, just like you did before. That will make it very easy to upgrade -- it's difficult to do when I don't know what files changed.
Thanks for the fix, the bug was not a real problem once you knew the workaround.