As others have stated, the big differences between the two won't come from model year, but the differences between the E90 and E93 platforms. Those differences are discussed in plenty of detail across the forum, you should have no shortage of reading material on that subject.
Not sure where you are in Florida, but I went through the M3 search/buying process in South Florida about 6 months ago. At that time, there was a comparative glut of E93s on the market, and I found that dealers were much more willing to negotiate on verts. If you're considering one, you might be able to get the seller down off his asking price pretty significantly...at least based on the market that I found a few months back. With that said, I drove both the sedan and the vert a good bit before settling on an E90, and I've been thrilled with the decision I made
Good luck whichever way you choose to go!