I'm thinking of getting a brand new one. Which one should I get, the 250f or the 450f? Is the 250 alot lighter (feeling) than the 450? How much less power are they? A couple parameters are: ~I'm 5'9" / 160lbs., In good shape. ~I'm approaching +35 class rapidly, only race outdoor style tracks. ~I come from the days of cr500's, etc. ~I've got a yz400f now, so I understand what heavy is. Any constructive feedback would be appreciated. Thanks!!