Originally Posted by dnomel

I think lower q is appealing mainly for small to medium road riders. Or maybe people who are just used to the older narrower normal width of around 140mm. Older road crank arms were straighter and it seems like most of the increase in q comes from the newer arms bending out more, independent of the chainring location. And some front derailers are wider than others, in the mechanism or the cage width, and just wont work sometimes with an old straight crank arm. I ride about a 54 and seem to like a lower q so often try to use old cranks, and a problem I've had is with some front derailers hitting the crank arm in high gear. I've got below 140mm q on 8 speed road bikes, a downside is using old parts and maybe a bit more attention adjusting and trimming the front derailer, and maybe a bit of rub in the highest gear, but I doubt the actual chainline is a problem. Also, if you have big feet or ride in regular shoes, your heal may hit the chainstay.
I probably couldn't tell the difference between say 140 and 150mm q, but 160 felt uncomfortable so I figured narrower was probably better for me if possible.