I know the Domane has shock-absorbing inserts. Maybe the Silque has them too? Otherwise what would make it "smoother"?

My only complaint with my Madone (from 2010) is that mass-produced carbon frames are more fragile than they should be. Otherwise I've been very happy with my bike. I did switch to a slightly narrower handlebar, otherwise it's very comfortable.

As noted elsewhere, I did loathe the new Bontrager Race TLR wheelset, and that might be the standard wheels for the mid-range bikes that Trek is selling these days. I found that they transmitted too much vibration from the road, and made my bike feel totally different. Of course it's possible that my Gatorskin tires were not the best tires for those wheels, and maybe the Bontrager tires that come with the bike combined with the wheels give a smoother ride. Anyway I only mention this because switching to a set of Mavic wheels (Ksyrium Equipe, IIRC) made me much happier, for about the same price. So if you don't like the road buzz you feel on your test rides, you might want to try swapping out the wheels for a set from one of your current bikes instead.

Happy shopping!!