I had a problem with the all-wheel-drive a while back,,,riding through snow trying to get to my buddies cabin. The drive stopped working and was grinding inside. When I took it apart it needed a clip that never was installed from the beginning. I emailed Steve Christini he was on it that morning getting me the new parts at no cost under warranty. Christini is one of those on the ball, honest, get it done right now guys, excellent service, above average, well I hope you get the point. While it was down I changed a sprocket on the front drive from a 16 down to 15,,,I was of the opinion that the back wheel had to spin too much before engadging,,,I like the change it is driving the front wheel at a closer ratio to the rear wheel. Not a lot of chances for real testing of all-wheel-drive on my recent rides the trail conditions are wet and the rear hooked good anyway.
Impressions of the KX450F for trail riding,,,,I love it,,,,the four stroke for down hill is nice with the engine drag,,,only wish there was a compression release for the real steep inclines,,,I always used my compression release on the XR600 like a jake/brake. No major altitude yet but from 5000ft to 7000ft the EFI is sweet. I thought I might want a Recluse but I never ridden one and wouldn't think I'd like it if it clutches going down hill,,,I really like the drag it has right now.
Pics of Chinese Peak by Pocatello, ID