[jem7vwh]

That chart has a ton of data, but I'm not sure how accurate it is, since it seems to think that the Wizard neck profile was first used in 1993.

Here's my understanding:

Original Wizard--these are the original block-style neck joint necks and the thinnest.
Thickness at 1st fret: 17mm
Thickness at 12th fret: 19mm
Radius: 430mm
Scarf joint.
Most susceptible to warping, but thinnnest.

Super Wizard--these are the 3 piece necks used on MIJ RGs between 1994 and 2002.
Thickness at 1st fret: 17mm
Thickness at 12th fret: 20mm (actually closer to 19.5mm)
Radius: 430mm
Still very thin, and more stable.

Prestige Wizard--these are are the five piece necks that come on the lower-priced MIJ RGs in Ibanez's current lineup. Slightly thicker and wider due to the five piece construction.
Thickness at 1st fret: 18mm
Thickness at 12th fret: 20mm
Radius: 430mm
Very stable, though a bit thicker.

Prestige Super-Wizard HP--these are the slimmest necks currently sold by Ibanez, and attempting to return to Original Wizard measurements (only wider).
Thickness at 1st fret: 17mm
Thickness at 12th fret: 19mm
Radius: 430mm
Five piece construction--very stable, very slim.

Wizard II--these are thicker than the Wizard necks, and generally found on mid-range MIK and MII RGs.
Thickness at 1st fret: 19mm
Thickness at 12th fret: 21mm
Radius: 400mm
Thicker front to back than the Wizard and with a narrower radius, making bends slightly tougher (still much flatter than Fender).

Wizard III--same specs as the Wizard II, just widened to fit the 58mm neck pockets on the new guitars.

JEM--this is a tough one. The JEM neck profile has changed a lot over the years, although Ibanez hasn't changed the official numbers they list in the catalog. So, here's the numbers from the catalog:
Thickness at 1st fret: 19mm
Thickness at 12th fret: 21mm
Radius: 430mm

On paper, this means that the JEM profile was originally like a Wizard II but with a flatter radius.

However, people who've played lots of them will you tell you that the JEM profile has gotten noticeably slimmer over the years to the point that it is now basically indistinguishable from the Super-Wizard profile. In fact, several of the late 90s JEMs (the DBK especially) seemed to just basically be Super-Wizard necks.

So if you play one of the first few JEMs (the LNGs, DYs, SKs), you'll find the neck profile to be a bit thicker than a Wizard.

If you play one of the middle year JEMs (the JEM7VWH for example), you'll find it starts a bit thicker but flattens out by the middle of the fretboard just like a Wizard.

And if you play a new one, I doubt you'd feel much difference at all from a Super-Wizard HP.

How's that for complicated?

 

[jem7vwh]

Anybody know what the extra square is on top of the truss rod in the wizard and Jem cutaways?
Looks like a double rod

I would imagine that's just the other part of the truss rod... the truss rod actually has two pieces that work together to create backbow or relief.