i had a bit of a look at them, and the inside is the same. it just has 3 or so mm less steel on the outside. mine uses the xt's reg/rec and 2 phase stator and it runs a 60w halogen bulb just like the xt did.
a heavier flywheel helps you stall a bit less i suppose. someone who knows more might chime in, but the lighter flywheel in my case was no detriment.
no swearing down here any more.