I just switched from a 2003-ish Chorus square taper to a 2009 UT Chorus carbon compact. So I have an 11sp crankset and FD mated to a pre-QS 10sp grouppo. Maybe it doesn't work as well as it should with an all 11sp setup, but it was an improvement in every way over the matching 10sp parts. I'm a skeptic, so I did not expect a discernible difference, but wow, was I wrong. A few years ago a guy who rides the same frame I do commented that he liked how stiff it was. I was puzzled at the time because I didn't think it was stiff at all, but it turns out that what I though was lateral flex in the frame was all between the BB shell and the pedals. Swapping in that crankset made it feel like a different bike--the BB feels rock solid; in fact, I scratched a new carbon frame off my wish list because of it, so I figure it saved me some $$! It also shaved off nearly half a pound, which is nice too.

As for the BB facing issue--I had some paint chipping off of the BB face, so I carefully scraped off the paint and just barely filed it with a sharpening stone (because it's flat and contacted the whole face at the same time, but I could not ensure the correct angle) and installed it temporarily until I could get in to the shop and have it faced. When I got there a few days later, the mechanic told me that they didn't even have the tool because all the frames they see are already faced, and he didn't think it made enough difference to justify the purchase. He told me that as long as it seemed smooth, it's probably fine. It's smooth as butter, so I just put it back together and have been riding it that way ever since. I'll take the slight possibility of shortened bearing life over the very real possibility of some shop mechanic taking off just a bit too much of the BB shell, making it impossible to get a proper install without lateral play. I did read about a guy who makes washers for this problem though, so that's always an option if you don't have a wide enough BB shell.