I have been riding an '09 Synapse Carbon for the last couple years. The carbon frame and SAVE feature provides a great ride. It is very effective at reducing road vibrations. This is a definite plus on long rides but is still appreciated on shorter rides as well. Let me tell you that vibrations can and will wear you down. I am a fan of the SAVE feature as I have compared aluminum rear ends with and without this feature. In addition to reducing vibrations it also maintains positive road contact in rough and bumpy conditions. My backup bike is an '06 CAAD8 (with full Dura Ace). I am sorry to say she gets very little attention. The Synapse can be setup in a relaxed configuration as well as in a moderately aggressive configuration. I have removed all of the spacers and now have a 5 cm drop. I have been told by my LBS that I can get even more drop by removing a large spacer underneath the headset cone. I have found that the Synapse Carbon was a very good fit to my needs and has been able to adapt as my cycling needs have changed.
All this said I would still look and test ride all the bikes on your short list and maybe a few others. How about a new BMC? a used Litespeed? or a used Merlin? I think my next bike will be TI.
Like you said buy the one that fits you (and your needs) best.
