Originally Posted by PeteHski

Well whatever stack spacers someone might require on the Domane, they are going to need another 28 mm of spacers on the Madone for the same height. So unless they have their stem slammed on the Domane, the Madone isn't going to fit. Likewise someone who wants the lower stack height of the Madone is very likely to run out of stem spacers on the Domane.

With all the other differences they are not the same bike, even though you could have an overlap on fits as you can with 2 or even 3 different frame sizes of the same bike.