Not got a Domane 5.9 but it is one that I have been considering though. Is it the 2013 or new 11 speed 2014 model that you are interested in ?
Also what size are you after ? I only ask about the size because if you are after a 2013 model then there are a few knocking about in the sales for about 3K.
Cracking bikes and all the reviews speak very highly of the IsoSpeed decoupler . My only reason for not getting one is that i think i want the new 11 speed ultegra but this will only be in mechanical form though as i cannot afford the prices for 11 speed Di2.