I ride a Yamaha, but a Banshee which is 2 stroke. If you plan on woods riding, etc I would stay away from the 2 stroke. The ONLY 4 stroke sport bike of Yamaha's I would buy is the YZF450. The raptor is junk, the warrior is just plain outdated, underpowered, etc. The honda bikes are AWESOME too, their 450 is great, the 400EX is a decent bike although slightly dated and underpowered now, they are selling them at HUGE price reductions, but no Reverse. The other one I would recommend if you don't want to spend the $$$ on either the Honda or Yami 450's is the Suzuki/Kawasaki Z400 twins. THey are the EXACT same bike under different colored plastics. I have several friends with these bikes and love them. They aren't quite as fast as the 450's, but are considerably less money, they have reverse, and are excellent all around quads for trail riding, duning, etc.
John