Well, since you have both I guess you can play with the MSI and judge for yourself. I've read some strange things about the KT7 Pro - mostly about bizarre multiplier issues.
On the other hand, I've set up four KT7s in the last 6 weeks with absolutely no problems whatsoever - okay, that's not true, but it is an awesome board, and, next to the KT7A, is almostly unanimously considered the best Athlon/Duron board available.
Have you considered doing the voltage mod on the KT7? It's pretty easy, and it really boosts the top end of your CPU. My board does 2.13v at 1.85v in BIOS, which allowed me to get my TBird 750 blue core from 1100MHz to 1208MHz. You can usually count on about 50-100MHz gain from the mod.
The KT7A should have the same solder points for the modification as the KT7, and until I learn how to pump up the voltage like that on a different board, as well as find a board that provides 1MHz FSB control in BIOS, I'll be sticking with the KT7(A!!!).