Jeff- Personally, so far at least (only had the USRG for a couple weeks), I prefer the USRG30...feel, tone, etc. Maybe it's the alder body that has a distinctive tone, and/or possibly that rod of steel in the neck.
I've had three RG3120s and ended up selling them since i prefered the tone and feel of my other RGs...I never changed pups on the 3120s, so that is something to consider. Brent loves 'em, and he's had plenty of Ibanez guitars, so it really is personal preference. They're a great value and I certainly recommend giving them one chance.
I noticed in the specs on the USRG...
...that it says "Wizard" but gives measurements more like an Ultra. Not sure what's up here (no, confusion with Ibanez neck specs?!?
The 3 USRGs I've played feel more like Wizards (not chuncky at all like my RGT, TX Prestiges, etc), but I may be out in left field.
If you don't want a figured maple top, just get a used RG570/550 with a Wizard & basswood (like the JPM) for around $300 and experiment with your pups. If you like pretty woods, try a 3120 or USRG. You could always contact one of the Jemsite sponsors that makes bodies and have a custom body made with a JPM layout. Endless possibilities.
As far as pups, I have not had the time to do much swapping. I like the SS in the USRG...lots of bark and bite, but I think I'd like the TZ better (again, personal pref)...I generally graviate to warmer, thicker bucker tones. Maybe I'll change it out this weekend. I'll be interested to hear your
comments once you've had a chance to some experimentation with that pile of pups!
Enjoy the journey.