so it doesnt matter how long they hold the pitch, as long as they get you there?
. . . once the nut's locked down it's not going to make any difference at all.
if not, i can just get the cheapest things that look right
I think they matter. I use Sperzel locking tuners on most of my Floyd guitars, because they make for fast string changes and solid tuning while I'm getting the strings stretched and settled in before I lock the nut on a new set. Also, sometimes I like to leave the string locks completely off my Jackson SL3, because I think it sounds better with them off, and those locking tuners certainly help with that.