I just scoped out both bikes too recently but then chose a Cervelo, but hey.
The Propel I had on test was bloody good, I mean really bloody good. Solid and fast and compliant back end. I initially thought it would shake my fillings out rattling along the lanes in Hampshire where I do most of my riding but nope, it flew over most of what I threw at it, very very nice bike.
I also tried a TCR with Ultegra on and that too was a blooming nice bike, bit lighter in feel and a bit whippy on the back end when hacking and climbing, which lets face it is what it's designed for. I really liked that too..
If I had to choose either it would be the Propel, reason? well I hack along the lanes at speed and the bike just felt right for that, I could get out the sadle and stomp and the thing just flew fast and light.. As for looks, well it looks whay better than Cervelos S5..