So, I tested a few more bikes tonight at a different LBS, each a bit different.
First was the Roubaix (with 105s). Three years ago the Roubaix was the first road bike I rode after owning my hybrid and the first road bike I had ridden since I was 22. I rode it mostly to recall why I loved it so much, and I indeed enjoyed it. Smooth ride, nimble, butt didn't feel a thing. But at this point in my cycling life it's not what I'm looking for. However, if you're looking for a slightly more upright but very nimble ride, this might be the one! (The Synapse is awesome too, and I would probably take the Synapse over it.)
Next was the SuperSix Evo (with 105s). It was much like my Caad10... a little more compliant but admittedly not by much. It handled very much like my Caad. But I'm looking for something just slightly smoother. Great ride though and lots of fun! Btw, the size was a 56, whereas my Caad in the same geometry was a 54. The fact that the overall bike felt much better in 56 confirmed that I really feel like I bought my bike too small.
Next was the Tarmac Expert size 56 (with Ultegra). The last Tarmac I rode was a size 54, same as my Caad, and I'm not sure why I did because it was too small. I tried the 56, and I LOVED it. It was smooth, fast, nimble, really just great. One minor nit was that I felt maybe the head tube was a tiny bit too short because, while I like my handlebars low, the stem was all the way up and I felt like it didn't give me room to bump it up if I wanted to. Perhaps I could flip the stem up if I wanted the extra few mm's of stack...
... which brings me to my next ride, which was a Tarmac size 58. I felt like I wanted a slightly larger Tarmac to see if it would bring the headtube up. The shop didn't have a 58 I could test ride, only a high end S-Works that they put on the trainer for me. But they fit me to it, and it felt incredible. I felt great reach, felt like I would be in a good aero position, and was sufficiently over the pedals to be efficient, with room to put the stem down. And the stack was just slightly higher, which presented a more comfortable but yet still aero fit given the reach.
I'm going to follow up with the store about getting a 58 Tarmac in so I can actually ride it.
Given the test rides so far, I think it's down to the R3 vs Tarmac (Ultegra) presumably in 58 (but need to try it first). I'm going to try to take each out for substantially longer rides so I can really put them through their paces.