Hi DOG! I'll give you my thoughts. I bought this motor:
Turnigy HeliDrive SK3 Competition Series - 2839-3600kv (450 size heli) (US Warehouse)
I don't recommend this one, at all. Even with an 11 tooth pinion, the head speed, on my 450 Pro DFC, is well over 3100rpm. Yes, the motor works and seems to work very smoothly, but it's not at all what I was hoping for. I'll probably end up ordering the Align 450MX 3400kv motor and I'll use the Hobby King 3600kv motor for another project that I have in mind.
So, I guess my recommendation would be to just get the Align 450MX 3400kv motor. I've heard a lot of great thing about this motor from people on this site and Youtube. It also got great reviews.
Good luck in your decision making!
I do hope that you report back with the motor that you decide to go with.