Mmh..too high makes a guitar unplayable. For example: I have an old Ibanez 2355 (ES175 type) hollowbody guitar from mid 70s - brillant guitar, very good condition and feel. It features two "Super 70s" Humbucker, awesome tone - but not much output. So I use a little booster to catch up the signal. If I adjust the heights of the PUs, the Pick touches the PUs while playing - which is pretty much annoying.....