Most Moots bikes are made to order so it's tough to get to ride one before hand. A common sticking point. Geometry is the key difference between the 2 models. The standard Vamoots is more suited for the type of rider that wants to be more upright with a less aggressive position on the bike. The longer head tube allows for less saddle to bar drop without the use of a positive rise stem or a ton of headset spacers. If you have neck or back issues or plain just don't like being hunched or bent over with to much saddle to bar drop, then clearly the Vamoots is frame for you.
The CR and RSL are similar in geometry but there are some differences, once again the the head-tube is slightly longer on the CR then the RSL (from sizes 52 and up) as well as the RSL having a slight increase in slope resulting in increased standover between the 2 models.
As you may already know the CR and RSL do not use the same tube set through and through. The RSL kicks it up a notch with the use of Micro-diameter seamless 6/4 seatstays for lightweight, and responsive ride feel. As well as 6.4 breezer style drop outs. This coupled with the new press fit BB30 makes for an increase in stiffness over the standard CR. So in summation the Vamoots is for the rider looking for a bike with the focus on comfort, the CR is for the rider looking for increased performance and a more traditional body position. The RSL is for the rider looking for the finest in Titanium race performance. I am happy to answer any other questions you might have. I have been working with Moots for many many years now and I have a solid understanding of how the process works. I hope I have been helpful in answering your questions.