That makes sense. After re-thinking my previous comment, I suppose another potential downside might have to do with somehow missing out on the numerous copycat offers that I imagine will arise. At any rate, although I'm surprised that everyone has signed on so quickly it does seem like a really good deal for all involved.
Probably not. But I imagine that when it comes to the details some angels might be a better fit than others for certain companies due to their networks, etc. Also, if I had a company that needed about $200k and I had one offer for $150k from Yuri and one for $200k from another similar investor I might only take the $200k instead of both - it would represent a (hopefully small) difference in available shares once it was time for Series A. This is all speculation though - while it seems like fun, I haven't yet been on either side of the investor equation.
Edit: phrasing.