To close the loop on this thread. I have been running 2.2 on my dev right through all the betas with 0 issues. I have tested and developed some plans around implementing the new features. My main add-on and my style have been updated by their respective developers. I have been running a "Coming Soon" feature in my Tips & Techniques forum to get people ready.
So, tomorrow I pull the trigger on Xenforo 2.2. Good job, Xenforo. Looks like a winner.