Yeah I don't know what they were thinking over there at Ibanez. For so many years, they gave out stacked single coils on H/S/H guitars. I mean, the point of the in-between sounds (2 & 4) is to have each operate as a single coil and cancel hum. But that doesn't happen with a middle stack. The IBZUSAC3 was a regular tall single coil. That appeared in some H/S/H guitars.
If hum is not an issue for you at all, then wiring it as a humbucker would produce a sound that's a little thinner, glassier, and more distant. That can give you a slightly more "hi-fi" type sound when combined with the outside humbuckers (in single coil mode)
If you want all sorts of fancy switching, or you're using a 4-pole 5-way, then you can wire it so the middle and
neck pickup are wired as singles when used together, but the middle and bridge are humbuckers when used together. I sometimes prefer the "un-cut"
bridge pickup with the middle pickup, so in that case, you would want the middle pickup to be hum cancelling for position 4, but single coil for position 2.
Sorry this post is so wordy. It's probably hard to follow with all the references to "single, humbucker, hum cancelling, etc." Basically the HS-2 is rather lackluster as a hum-canceller. So unless you need hum-cancelling from it for noise reasons, you're probably better off wiring it as a single.
