from what i understand Squidster, they haven't changed all that much. there was some starting issues with the '01, but once they are jetted correctly and are run in, they start great. it seems to be a bit of a myth that has grown.
if it was me, i would probaly take the '01 model and spend the extra dosh on bits, but.............
early model WR/YZF's did like to snap cranks, and i think Yamaha has worked on that problem for 2002, but they won't say it of course.
the busted cranks did happen on the first batch and usally happened with only a few hundred kays, so i guess it's the luck of the draw when you buy one.