Yes for the extra $30 get the metal gears. I cant imagine that metal "wears down" faster than a carbon fiber composite, I would have to see some data on that one. Matter of fact there is an ad in the latest AMA magazine that shows the difference in the gears... the carbon is rated at like 4 x stronger than stock, the MG is rated at like 16 times stronger and the new titanium is rated at 40x stonger than stock.

For the $10 each get the MG.