@rocthrower, thanks for pointing out the better levers and brakes on the 2018 Domane SL5 Gravel compared to the SL5 Disc. I had assumed that only the tires & paint scheme were different, but the Trek website and your post prove otherwise. Yeah, the SL5 Gravel version looks superior in all of those aspects (I agree re. the color too).
I'm interested in getting a multi-purpose commuting / wet riding (fenders) / occasional gravel bike and am looking hard at the Domane. I appreciate your info.