Ditto what Clay said, I have ridden both 450 & 570.
Other obeservations
seat of the pants the 570 lacks the 650's grunt more than I thought it would
the 570 is a gas guzzler it seems only 12km/L compared to 15-16km/L for the same riding on the 650
the 570 is an enduro weapon............not sure about the desert yet though !
ease of riding, handling, turning, 250F ride feel is the same as the 450