As someone who just went from a Trek FX hybrid to first road bike (Domane SL 5 disc), a few observations:
- My biggest concern was my back, tons of issues over the years and lots of pain, I've held off on making the transition for years. However, I've found the Domane much easier on my back, kind of counter intuitive but especially on climbs, I find the more "aggressive" posture actually seems to help avoid a lot of back pain! I'm actually getting into the drops on climbs as I like how it stretches my back out and gives me another position to get into.
- The bike is so much more "easier" to ride, that I think it helps quite a bit with with speed and fatigue, you hardly feel all the road chatter from bad roads and paths.
- Last and not least, It is just a lot more fun to ride!