I put plenty of miles on my Eroica bikes every week and don't have a modern bike any more. For a while I had a modern Trek, complete with brifters, etc but I got rid of it because I found the Eroica bikes to be more comfortable and almost as fast. If I was still racing I'd be all out carbon, electric shifting, etc, but for my type of riding (centuries, commuting, half-centuries, etc.), the modern conveniences like index shifting and clipless pedals only constitute incremental improvements on the old ways, not exceeding the value of aesthetics and retrogrouchiness in my eyes. I also enjoy the slight notoriety of riding with my carbon-equipped friends without giving up ground to them.

I have made a few concessions to practicality. Although I find wool to be far superior to synthetic during colder weather, lycra or similar comes out when it's hot. Also, pretty much every weekend ride has over 5,000' of climbing, including some brutally steep grades (not to mention that I'm an old guy), so vintage racing gear ratios are never going to cut it...my low gears are in the 20s or 30s.