I bought a Cannondale Synapse about 9 months ago and I am very happy with it. I had it mounted on a pair of Mavic Kysrium Elite wheels during the warm weather months, and the bike rode fantastically. Because of the drop handlebars, you can sit as aggressively or as relaxed as you want. During these winter months, I have it mounted on my Wahoo Kickr Core smart trainer. I highly recommend the Cannondale Synapse.
The $1,000 price is extremely attractive even if used, but as other posters have asked...is it the proper size for you? The comfort, enjoynent and fun of riding the Synapse will not be evident if the bike is not the proper size for you.