This week I'm buying my first cross bike. In my former life I was a fairly hardcore rider / racer — road in the 80's and mountain in the 90's. In the last three years I started riding more seriously again. On average I ride my mountain bike 70 to 100 miles a week — mostly on our local Rails to Trails network. Not a ton of miles, but enough to make me feel justified to shop a new bike — something faster than my mountain, but durable enough for the trails — enter the cross bike.
Currently I'm shopping a 2010 Specialized Tricross. I'm between a Comp and an Expert. A lot has changed since my last competition bike back in the 90's so I could use some advice. Specifically: the difference between SRAM Rival (+$300) and Shimano 105. I don't "mind" paying more for the Rival if it's worth it. Any insights?