I use comping for vocals a lot but I still punch in most of all my stringed instruments.
been doing it this way for years, old habits are hard to break. but for me its more about flow.
get it right, get it done, finished.
creating too many comp tracks for me I seem to lose something in there, the groove, sure but more importantly, the flow, the main idea, the reason I wrote the song, comping can turn that in to an over produced version sometimes.
less we forget, sometimes mistakes make a song more realistic.
jimmy page will testify to that, as he is one of my favorite song writers, producers.