So I bought my 2009 YZ450 about a year and a half ago and I'm on my 3rd sprocket. In all fairness the first one that the bike came with wasn't in the best shape. So in all actuality I'm on my 2nd one that I bought. I've put 58 hours on the bike in that time and it seems that these 450's really go through the sprockets. I ride exclusively MX and I clean my chain every ride and re-lube it both post wash and prior to riding. I've been running a steel front and aluminum rear. I've tried an inexpensive JT sprocket and the more expensive renthal sprocket. I came from a 2 stroke and this is my first 4 stroke so I'm not sure if this sprocket wear is normal for these big 4 strokes or not? I check my rear axle alignment with a set of digital calipers, not relying on the axle blocks so I know it's running true. Finally to my question, has anyone run the dual compound sprockets like the twin ring or the supersprox stealth? I'm wondering about the additional rotating mass affecting the bike handling in the air versus the longevity? I'm not looking for input on recommendations for gearing, I'm happy with my 13/50. I'm just looking for pro's and con's of running a dual compound rear sprocket, and what you've run with an idea of longevity? Thanks in advance for the replies.