2 years ago I raced Keith Johnson's (National Mxer) KTM 520 which was big bored to a 540 at Central Village MX track in Connecticut. Talk about a beast! I 3rd gear started and wheelied down the entire start straight and when I looked back, I had to be about 150' ahead of the entire rest of the pack. That bike was INSANE, but handled like a KTM. I lead the race up until the thing stood up in a turn and I highsided over the berm. It took me about 2 minutes to fire it back up and go. But, what fun while it lasted!
My Honda CRF 450 is so well mannered and is probably THE best bike I have ever ridden. I could easily woods ride with it as well as race MX/SX with it. The craziest bike I ever rode though was an ATK 700 Intimidator. 2 stroke. Don't want to be "whiskey-throttling" on that thing. It will launch you into the stratosphere.