I am 15 years old, 5'10", and weigh 155 lbs. and my dad is 6'0" and 200 lbs. We are either going to buy a new 2008 Yamaha YZ 250F or a new 2009 YZ 450F. This bike will be for both me and my dad. Right now we both have a 2005 Yamaha TT-R 250 and we both have been riding for a long time and are very good riders. We are starting to get more into jumps also. So, which bike is the one for us?