Pretty much word for word what I was going to say. If you plan to do any kind of work to either the promaxx or sm heads, I don't see any advantage to not buying the TFs instead.
Trick Flow, in my opinion, really nailed it on quality of work and parts for the price. Someone has to be the guinea pig in these situations, and I'm not sore about it being me in this situation, but I without a doubt would have gone TF if I had the numbers in front of me on Black Friday.