It isn't so much the total LOC that I write (and delete) in the process of making a change so much as it is the friction and mental overhead of the change. The more I can focus on making the semantic change that I care about, the better.

Admittedly my vim setup doesn't even have YCM because I don't care enough to do it. But there are other minor things (swapping : and ; in control mode, mapping jk as <ESC>) that I've done that I hate working without now.