dmoney wrote a review of SRAM X.9 Rear Derailleur (9-Speed) on November 23, 2011
i just got the x.9 after bending an x.5 by pedaling to hard uphill in my highest gearing. The x.9 seems to be suiting my needs well. im running an eight speed drive train, with an x.5 shifter, sram crank, sram casette, and a shimano chain. Its smoother and shifts much better than my old x.5. I like it. the x.9 seems to be a lot more durable than the lesser models also. Also, i will be able to use this to upgrade to a nine speed drivetrain in the future. The pricing here is also a plus. The x.9 is only 40 dollars more than the x.7, but the x.0 is almost 140 dollars more than the x.9! Its good upgrade for a reasonable price. Unless your looking for some carbon, and your drive train is an 8/9 speed, this is a great option.