DL said:

The situation with FF like systems is you have a whole bunch of people adopting, adapting and scrutinizing the code either as an end or a means to an end. Coders have a lot of incentive to keep it clean and well built (which doesn't mean they will, just that there are reasons to).

The benefits I've found to that aspect of open source is: [a] not having to wait for a major product rollout to get useful tools; [b] only getting the ones you want, without having to take the whole bundle.

I'm not at all entrenched in the give-and-take at Mozilla... too many other discussion boards to visit, already. But I have the impression that (as I suggested to Steve G. about T-bird) even a n00b like me, if he found the right k0|>0r to ask, could get a new add-on built, tested, and posted for downloading.

The feedback on the Themes and Extensions pages at Mozilla is helpful, too. You get "Consumer Reports" on the pieces and parts before you download.

You don't get any of that with Microsoft.