I'm for all those reasons. It's hard to tell on this board for proper/ideal/nitpicky/anal stuff like chainline where people are trying to dial in to the nth degree (41.5mm just isn't *good* enough) or if they're trying to get something ramshackle to work or are a first timer who wouldn't know the difference, and everyone's somewhere in between on something or other.

I'm mostly in the latter faction out of ideology - something in me *likes* being a little bit off what you're supposed to do or making stuff work that's not supposed to against all odds. I like having a little more slack in my chain than perfect so that when I balance I have that half cm of non-engagement to float a bit, say, and I think conversions are cooler than fixed specific road frames, and I especially love stuff like your version of the project of the disk hub conversion. And I made several posts here about bbs and cranks because I didn't know whether or not my bike would blow up if I just did what I thought would work.

As for chainline, agreed and disagreed - wear and noise, meh, and if you're dropping chains, well, something's more wrong than a mm or two of chainline. I'd consider multispeed drivetrain problems to be: missed shifts, tuning deraileurs (and throwing them into your spokes), wearing out my favorite gear and needing a whole new cassette, breaking shifters that have more moving parts than a car (and cost almost as much), and not getting to experience the fun of a fixed gear bike or the carefreeness of a SS. mms of chainline I think for me is the most overthought and least significant part of building up a fixed gear bike. I guess it's also practically the only thing you have to think about, so touché.