Need a new bike!!!! What do I get??

I have been riding two strokes my whole life and am looking to buy a new four stroke. I have a yz 250 and a rm 125 now and dont know if i should go with the 250f or 450f and which one to get. I mostly ride woods and am tired of not having enough power, trackin, etc with the two strokes. Im a small guy, 5'8'' 155lb but have plenty of riding experiance. Id rather have more power and not need it then not have enough and I am use to alot of power ( I have a cbr600) but am not sure if a 450 is just too much. With that aside, what bike do I buy (looking at 07 or 08). Even tho I ride mostly woods I would like to stick with the kxf, yzf, cfr, rmz, or sxf instead of the klr wr etc. If anyone has any opionins on what is the better bike for '07 '08 and anything about the 250 v the 450 let me know. Thanks, Matt

I love the idea of the 450...power whenever you need it! But, I was talking to a guy who races GNCC and who use to have a ktm 450 and switvhed to a 250. He said even tho the dry weight of the 450 is not much more than the 250 it feels a lot more while riding. He said the engine pulling through tight turns makes the bike feel heavy and really wears you out riding for periods of time. He also said that a 250 will do anything you would need to do while woods riding and unless you are racing in the motocross class a 450 is not necesary. Any thoughts?

I decided to buy an new leftover 06 crf250r for $4600 out the door. Cant beat that. Ill let you know how it goes.