A few weeks ago I was able to test ride the Ruby Expert and the Trek 5.2 WSD on the same day. The LBS guy told me that comparing the two bikes is like comparing a BMW and a Mercedes - both really good bikes with really good components, but people just tend to prefer one over the other for whatever reason. He said I'd just need to get on each one and take them for a spin and I'd be able to tell the difference and which one I preferred. Personally, I liked the feel of the Ruby better. I can't even pinpoint why . . . something just felt better about it even though he had the saddle, etc. set up the same. I know someone who did the same thing but preferred the Trek.
This coming weekend I'm test riding a Giant that is going to be built up with fit specs from someone recommended by my physical therapist. I've found that test riding can be kind of fun, and it's a great learning experience.