The axis had it on the lower horn for a concern of switching the pup while tapping (hitting the selector with his forearm) I also wonder with the Axis if the concept of having the selector & pot in the same cavity was considered a way to cut less wood out of the body.
Ed said in 91 he really enjoyed the guitar and was using the neck pup (which he called the front pickup) more since it was created to his specifications and he was happy with the sound.
Peavey Wolf - the pickup selector was moved to the standard LP spot, but it is upside-down as Eagle said (up is bridge, down is neck) which prevented a tapping forearm from switching the pickup (supposedly). Tone knob was added, though I don't think Ed ever touched it live, and he gravitated toward the flat top specials with the maple caps mostly (which only had a volume pot) live as time went on. (A Peavey wolfgang Special is the only guitar I've ever left stock. It never needed anything except a fret dress & a NOS bridge as I played it so much my sweat rotted the saddles some how)
EVH Wolf - Addition on low friction volume pot (which I do not personally like - just my preference) EVH branded Floyd rose & slight movement of pickup cavities. As a guitar mod junkie, I prefer the standards.