My bike before the KLX was/is a '96 Ducati 900SS SP, 450lbs & 83HP (my dream bike).
I can't even imagine riding an open class bike on single track!
My KTM200XC-W @ 230lbs(?) and 40hp propels my 140lbs so fast, I'd be in trouble with anything more...I'm fast, but never gonna be that fast...too much work for no real gain. As Klxster has said, the concentration level required is so high it removes the fun factor for me. Now maybe if I had an Open Class riding buddy to chase things might be different.
I love the KLX because I can grab a hand full of throttle and still be alive after it decides to get going...

 

Max, one thing you can do with a open classer on single track is roost the holy hell - even put out of commission - anyone ******* your ****, anytime, anywhere, from any speed, so long as you can survive the event yourself.. It sounds terrible.. anyone faster than me in a XC, I let pass.. anyone tries forcing me off my line may end up having a bad day..

 

The husky isn't much different than a 250 2t...220lbs, 50hp...same with 450 mx bikes. I see a lot of these bikes on the trails, even single track!! The husky 510 is a stroked 450 with mild cams and ignition mapping(vs. full on mx bikes) designed for performance and longevity, like the KTM rfs engines, heck it holds 1.7 litres for oil, the KTM lc4(Dakar king)holds 1.5l...What's the big deal? Power envy?