Plz help: R2 vs R3

I agree that in general R3 is much worse than R2, especially if a year is as competitive as this one. However, your chances of success also depend on the schools where you are applying and on whether you have something unique in your profile.
If you have this uniqueness, it's good, as you could get in even in R3 (some schools fill their R3 places trying to maximize the diversity and thus admit applicants with weaker stats but with non-trivial profiles). However, if you feel there's nothing 'wow-ish', compared to the typical class member of the school you want to get into, I would advise to postpone your app to the next season and strengthen your profile, because neither rushed app for R2, nor well-prepared, but with average stats for R3 will probably get you in.

I think it would depend on the school and how badly you want a MBA right now. If you applying for a safety school, I say go for it. Most likely your credentials would be above par. Plus, there's little harm done if you apply again next year when you will have the same or better credentials. If you are trying to apply for a reach school, I would say just wait until next year, unless you absolutely want to be in the class of 2011.