The S2170 is quite frankly a controversial guitar. However, most of the controversity stems from discussions among people who are used to the 90ties S-series guitars, and the S2170 is quite a different beast. It doesn't really help the biased discussion that it was Korean-made, which for some people is a complete heresy (as Prestige = made in Japan).
I have a 2007 S2170FW (Burl Poplar) that I got used about 1.5 years ago.
Overall, the mahogany body resonates well even when played unplugged, and is very comfy. The Dimarzio/IBZ pickups (kinda medium-high output) are better than their reputation I think, but they are definitely not top notch. They sound well in the guitar, good note separation in cords even under high gain. The PAF Pro-ish neck humbucker is definitely my favorite on the guitar for soloing. But if you're into more agressive metal with searing distortion, the pickups will be too weak. The ZR trem is fun I think, very spongy and easy to maintain. Only bummer is that the cosmo black finish might rub off if you don't wipe the hardware clean after playing. The trem rings are super-bad quality coating, every S2170 I have seen had tarnished rings - I polished mine down to the metal, which looks actually decent and is a cheap solution.
The main issue with the guitar for most people is the neck shape and fretboard radius. It's marketed as a Wizard II, but it's different to the one found on current Indonesian-made Ibanez models. It somehow comes across as "beefier", with thicker shoulders. It also has some kind of semi-glossy finish that is different from the regular satin-ish Prestige neck finish.
The fretboard radius is 400mm (less flat than your RG3120, but way flatter than the JS1000). Yet, the bridge's radius is 430mm, resulting in slightly less low possible minimal action. But there are tons of guitars out there with such specs. Just don't expect sub-1mm action and you will be fine. I played around a lot with its action, and I like it now quite a bit. It's low, not as low as on others I play, but low enough (1.2-1.3mm maybe @ 22nd fret). Together with the fatter neck it is refreshing to play - plus very good practice to get your hands strong and flexible
If you are used to a Super Wizard neck as on your RG3120 (or if you "think" you can only play on a pencil neck), it's not for you. The neck on my S2170FW is the fattest neck in my small Ibanez collection (RG8470F, S540CG).
Also, S2170s were quite overpriced when still in production - the very sexy tops did not really justify that. They are no Team J Craft Prestige (although, that seems to mean something else these days than it used to...), although the fretwork and overall worksmanship on my S2170FW is great. The guitar can scream and purr and sing crystal clear. All it takes is using it for what it can do.
Play one, try it out, if you don't like it, leave it - there are so many other fine guitars around. I personally hang on to mine for the moment.
What kind of trade do you plan?