I have had a few of both,best 4 stroke was my 04 crf 450,some one had spent nearly 4 grand on it.Was really quick and smooth,but if you gave it a fistfull it was straight in the air.I am only 5ft 8" so it was a bit tall for me and heavy.Got 2 07 cr 250s now selling one soon.For maintenance costs,2 stroke every time.You could blow a 2stroke to bits and repair it just for the cost of a top end rebuild on a 4stroke.Power wise 250 4stroke equivelent 125 2 stroke,450 4stroke=250 2 stroke.hope this helps