Like with EFIS's, most RV builders have experience with the one that they decided to buy (usually for good reasons!), and therefore it is hard to compare them from what you get posted. The good news about both Trio and TruTrak is that both of them work very well - either can control an RV, and do so with pretty good user interfaces.
One thing to think about is if you are going to interface to fancy NAV or EFIS equipment, you'll want to talk with the folks that build (or fly) those fancy things to see how well they have designed their interfaces to autopilots, or if they designed around a particular autopilot - in which case, that would probably be the best choice. Most all of the digital Autopilots work great and install almost identically if you are looking for standalone capability.
Paul