Our company-wide bug database has ~2000 open issues at P1 or P2. That's for ~10 products across 3 divisions. Some of those have been in there so long that I think they should simply be closed.

My project is fortunate in that we're green-field development, which means we've been able to keep the bug count low. The project that we depend upon has ~20 bugs to fix. That's run by a different group, but we'll pitch in and help when we get close to releasing our stuff.

But, back to the original point: I suspect (based on my experience) that the ideal Agile team size is 4-5 devs with 2-3 QA. I also suspect that success is really governed by the quality of your team. The Agile process can't turn bad programmers into good programmers, but it does remove all of that waterfall crap so that good programmers can get on with being good programmers.