I suspect you won't hear as much from the ones that had a hard time switching:

http://en.wikipedia.org/wiki/Survivorship_bias

I don't think that applies here at all. Why would people who had a hard time switching be any less visible? I would think they would be a lot more likely to talk about it, like how people are more likely to write a review of a product they hated than one they were content with.

Pick the team with the lowest attrition rate. The team to which I was assigned was losing someone every month and I was allocated as cannon fodder to stop the bleeding. It didn't end well.

Yes. If you want to switch teams, and the team that you're switching to wants you, then it's basically a done deal. Feel free to send me an email if you've got more questions.