Well, I have a Tactile Pro 3 here sitting next to a Unicomp Ultra Classic. And in all honesty, they're quite comparable in terms of force required to actuate.
They feel quite different though. The Unicomp has a much more noticeable travel distance to the keys, and a very sharp tactile point. The force curve doesn't feel much like it changes after the tactile point though.
The TP3 feels like a shorter throw, and the once the you get past the tactile point, the force required to depress the switch seems like it drops off dramatically.
It's hard to explain, but the buckling spring feels "cleaner". Like there's less going on in the switch. The TP3 feels like there's a lot more things moving when you depress it (which, in truth there are).
Hope that helps!