I use pitch shift for +1 and -1 for live gigs instead of having three guitars. Works fine as anything. It is not possible to be perfect. I just don’t use the Transpose inside the rig (as opposed to slot A) because it doesn’t show on the remote. I almost got fired from a major label gig for starting a song in the wrong key (Transpose was set in the rig menu but not visible on remote)
Also use it live to transpose -1 or -2. It is not perfect, but you get used to the latency surprising quickly and it works. Record the result and you will see it is tracking very well unless you start using odd distorted chords.