I keep seeing conflicting reports on this. Sounds like trim was introduced to SRAM in 09 or so, but has it made it down to Rival? I test rode a Force build today and couldn't really notice the trimming action taking place.

Force has trim on big ring in front, not small ring. I have it on 2 different bikes and find it useless if my fd is dialed in.

AFAIK they've always had trim, but I think it might have changed rings at some point.

All levels have the trim on the large ring, Force and Rival used to have it on the small ring, I think the switch was done in 2010 and newer. The trimming action your referring to doesnt happen automatically like Shimano's Di2. When you shift to the large ring, you can tap the left trigger again to move the FD a few mm back but still stay in the large chain ring, tap one more time and it drops the chain to the small ring. This is designed so that you can stay in the large ring and access more of the low gears without chain rubbing the FD cage.

Interesting. So is SRAM just designed well enough where trim really isn't much of an issue? I'm coming from a Sora/Tiagra triple and am just used to trimming so often that it's become part of riding for me.

yes Rival has trim on the big ring just like Force. if the FD cable has to much tension on it though it will not trim you will just have 2 clicks to go from big to small ring. as grwoolf said though on most bikes if the FD is set up well you wont need the trim.