I am buying my first 29er. I find the TT length to be longer on the med frames as apposed to med 26ers. I am quite comfortable on a 26er with a 23.5 TT

The med size 29er has a 24 inch tt
The small size 29er has a 23.250 tt

I am thinking about going with the small frame, would this be a mistake ?
I would have to run a 75 mm stem on the med frame. A 90 to 100 mm on the small.

The other thing to think about is that the small frame is speced with a 80mm fork while the med frame is speced with a 100mm I wonder how much difference that would make with 29 inch wheels.