I went to SRAM Rival last year. Best decision I ever made. I have used bar-end shifters, and Shimano STI (8 and 9) and the SRAM stuff is fool proof. I highly recommend it. I run a 38/48 on the front and 11-28 on the back. I have yet to find a course where I ran out of gearing.
BTW, yesterday I bent the right brake blade (lever) in a crash (long story). I was able to order up a new blade as opposed to Shimano where I would have needed a whole new lever. That in itself is AWESOME!
With SRAM coming out with carbon for the Rival, you can probably find some aluminum Rival on ebay cheap.
I go 9 since I feel that the 10 speed is just so closely spaced that there may be a higher chance of things getting gunked up during muddy races. Since there is more play in 8 or 9 speed drivetrains, I feel thay they hold an advantage over the 10speed stuff. Just my 2 cents.
SuperTick, I hear you, but after a year + on 10sp, I found my fears to be unfounded. The 10sp gets clogged just like 9 when there's a leaf in the cassette, but other than that, it hasn't been a problem.
I run a single 42 up front, and it's nice to run a gutted Rival lever to match the rear lever, as opposed to a separate Cane Creek or the like.
The more and more I race cross the more I realize how few gears I need. Being fast in the transitions and having your race be as flaw free as possibleis more important than whether your are riding a 9 or 10. This year I have switched to a 40 up front with a 12-27 in the rear. I find that my racing is much more fluid. I watch many riders fumbling between the big and small ring and it costs them time/energy/places. I do have another bike with the standard 38/46 if the course requires such. Let's put it this way, I have been on the podium many more times this year with the single ring.