My 2p, I used a shunt with a sling as a chest harness, with mico traction as back up. This is for single pitch stuff. Sometimes I've tied a knot just above the deck. In my mind they both have failure mechanisms but the chance of both at once seems to be fairly minute when working vertish stuff. I got a shunt because that's what someone else used, used it once and didn't trust it. I got a micro traction for non climbing stuff and then thought it was worth a bash. I'm pretty happy with both on one rope.
I've also just used a grigri with a knot every once in a while.
I've not done loads of top rope soloing though. Usually a couple of sessions a year.
