Another thing to consider...you can get a flywheel weight for either of the 2 strokes, and that will knock down their hit even more.
With the KDXs, it is all about throttle control. It CAN light up, but you have to make it do it. If you just want to lug around in the woods, don't worry about the "hit" because you'll never know it is there. I like the fact that my little KDX200 can go very slowly, but when I fan the clutch, the personality changes a lot. If you put a big enough flywheel weight on it, you will de-fang whatever hit the bike has. I bet you will be able to handle the KDX just fine.
The KLX just never interested me. It seems like an odd bird. A CRF250X or WR250F, now that is another story!