I agree that it's a little different, but not much. I've got two new 30" shafts that I've been trying out the past couple weeks and mostly the difference is in the shaft taper/ferrule/tip/etc etc etc.
The extra inch really isn't *that* noticable, compared to a similar 29" shaft.
One of the shafts I have is a 30" Predator Z2. The other is a custom 30" shaft I had to my specs, slightly different than the Z2 (tho more similar than not). I notice a huge difference between those two 30" shafts, on the same butt -- certainly more of a difference than between any of my 29" shafts and my 30" shafts.