My experience is with carbon or aluminum, so I can't answer your questions. FWIW, when I got my carbon bike, I didn't really notice much difference between it and the old aluminum one other than the carbon offering a smoother ride on rough pavement. I don't feel particularly blown around by the wind on the carbon bike, unless it's very very windy in which case I prefer not to be riding at all. But I'm not exactly lightweight.
One thing that comes to mind, since I've discussed different frame materials with a friend who has a fleet of steel bikes, does lots of long rides including some tours and tends to carry lots of gear on his bike -- with carbon you are very limited on your ability to add racks for trunk bags, panniers, or larger handlebar bags. If you think you'll want to have that type of gear on your bike, I think ti would be a better choice.
I'm curious, on your Serotta, which parts are ti and which are carbon?
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles