A linemans belt is typically not loaded much so a standard Prusik works fine. On my tether, I like a Prusik as well since I don't want to reach up and accidentally release the VT or other hitch. Unweighting, by standing on platform to adjust tether is just a compromise I will deal with. Pulling on a friction hitch that is designed to release under pressure may not be safe, IMHO. I know, backup knots at tether end and all but do you really want to slide from your friction hitch to your tether end uncontrollably? Most people are supporting their entire weight on their tether so this connection better be secure.