If you compare all the reviews, there is more consistent praise for the Synapse. The Domane...redesigned this year...previous gen is reported to have a split personality...very stiff front end and uber compliant rear end. Many find this contrast distracting. The Emonda in fact gets better reviews than the Domane for ride quality even though it maybe a tick stiffer in the rear because of no iso coupler. If not riding horrible road consistently, I wouldn't opt for a bike with suspension. My personal opinion. Also, I wouldn't be an early adopter of the new Domane either. Reports are mixed about the front end.

All said, I choose the Roubaix. It isn't because it is a much better bike than the Domane or Synapse...its isn't, but the design for me is more reliable. The Roubaix can be had with English threaded BB with its excellent 10r carbon frame on its Expert model. This is big compared to less reliable BB90 on the Domane and BB30 on the Synapse. Seatpost is big. Synapse uses a 25.4mm post with limited aftermarket availability and the side by side bolt design of the FSA post that is spec'ed for the bike isn't as good as a pleathora of aftermarket posts that can be used on the Roubaix. I like Trek bikes...tech is undeniable...But...BIG but...I don't like BB90 with carbon on steel bearing press fit and their seatpost mast design stuck with 1 bolt seat clamp sucks big time. There are complaints on the web about both. Point is...this proprietary tech is needless when a superb Roubaix can be had with English threaded BB and 27.2mm std seat post which will accommodate a 2 bolt carbon post where the saddle tilt can't slip. Of course just about all of this goes over the head of the uinitiated however after purchase, an uninformed buyer will be stuck with the outcome after they throw down their 3 large. Buyer be weary when delving into the world of tech where companies are thirsty to separate themselves from the competition to carve a marketing niche and turn a profit. Look no further than Microsoft with all their tech, they get their operating systems right only every other time. Perhaps contrived