It is a shame most of you guys would have disappeared by now (for this site does not email notifications when new comments are received).
A lot of work-flow improvements and fixing of stability issues, are from reports I put into Opera. I spend a lot of time doing research on the web with opera, having over 400 page tabs open some times. Because I am a heavy user, I tend to see all the bugs and stability problems you don't notice with ten tabs, or short sessions (the transfer memory leak, printing related stability issues were some of the recent problems I found and reported, a lot of adjustments and a number of work-flow improvements to 9.5 were ones I submitted). I am also a computer scientist, and do work-flow related design.
I have gone through the ups and downs of Opera releases and there are normally problems, sometimes (like the release of the 9 series, which were worse than normal, and you get sick of finding new issues and sending reports, but a ten hour day is a lot slower if the issues cost an extra 20%, or more, on your workload)). I notice that Visual C/ms featured in a fair few bugs. I don't know what happened, wherever they converted to a MS based development system, new team or whatever. There are a lot of improvements from my suggestions in the way the work-flow works, and at last I am happy with 9.5, but they tend to ignore some of the new big feature improvements I want, that would just crush the competition from a professional users viewpoint (but also very good for normal users). Opera is probably still the top dog, but If I took all my suggestions over to Firefox, would it be? All firefox would need (if they don't have it already) is comprehensive testing team, with brilliant ideas for improvements, and a brilliant development team, with more ideas, that could take all that and program without errors. You would also need a couple of brilliant individuals to guide the process and strategy.
I would say give it a try, but when you do just remember, there is a lot of hidden features that might not be obvious without some use (also read the documentation to find them).
Sorry for the quality of the writing. it is rather late here.