I finally got around to test riding a Synapse yesterday...along with a half dozen other bikes, all in an attempt to narrow down what I was hoping would be a shrinking short-list but instead had been expanding at an alarming rate!
Anyway, the Synapse was everything I had hoped it would be, and even though I probably went into the shop predisposed to favor the Synapse, it really did earn first place amongst the contenders based on ride feel. It glides over the pavement like a hovercraft, on a cushion of air; and, like a hovercraft, it seems to move forward without the slightest provocation.
Close second wound up being a Giant TCR 1 composite. It feels the slightest bit heavier in my hand, which may be enough to cause me to choose the Cannondale, but once on the road its ride was excellent.
Tied for second was a $7000 Merlin Ti bike that my LBS employee let me ride just for comparison. Remarkably responsive bike, I'm just not sure I'd want to tolerate that much "road feel" when I'm in the saddle for 8+ hours. Oh, yeah, plus it's $7000!
But the Synapse is definitely holding on to the #1 slot going into next week's planned more thorough test rides. Didn't like any of the Specialized or Kestrel bikes I tried; in fact, I found the S-Works Tarmac unbelievably uncomfortable, though I think most of that was due to the handlebars.