OK, I know this may stir things up a bit, but, my RB'd KDX220 with KX front forks was as good a woods bike as I have owned and I've owned a lot.
For certain terrain (mainly the tight, steep stuff here in the NW), a nicely outfitted KDX is very hard to beat. The way the engine puts power the ground is perfectly fitted to this type of terrain. It has dated ergos, but it is also more comfortable for long sit down rides and with a few mods, it can be set up nicely.
Yes, the Gasgas better brakes, clutch, suspension, etc. and it is about as good a bike as it gets for woods riding. But, the KDX is very capable and in the right hands is a woods weapon.
If I were to ride the same section of terrain on my old KDX220 vs. my Gasgas, I am sure the times would be so close it would be a wash. But, I am an old, slow B trail rider and dont need a kick butt race bike. I just like riding something different than everyone else.
Funny thing, I know for a fact that I was fastest on a Yamaha WR250f! I dont know why, but that "girls" bike suited me well and I was so confident on that thing that I could really push.
Different strokes for different folks.
Like I said, I have a special place in my heart for KDX'