I have a 55cm titanium disc, that can take upto a 35mm tyre. Currently it's running sram etap hydraulic 1x11Wanted, a titanium disc specific gravel bike or gravel bike frame, size 56 cm ( large ).
My CAADX is officially a cyclocross bike but I think it is pretty much what a 'gravel bike' is. I went out on it yesterday and did a real mixture of surfaces and terrain and it coped with it all. The one part of the ride that it faltered on was a rocky section of the Pennine Bridleway - I would prefer to ride my mountain bike there. If you don't ride on surfaces as extreme as that and are not bothered by losing a little bit of top speed then I think a gravel bike would make a good 'do everything else' bike.i would probably off load my other bikes if I got a Ti, they seem proper good all rounders these gravel bikes