I thought the VDY and the PBK were the only 2 JEMs that had the ultra thin neck. I dont recall my VSK being ultra thin but it has been SOME time since I played on one so I could be wrong. Actually now that I think of it, I am sure te only 2 JEM's to have the ultra thin wizard neck were the PBK and the VDY.
The RB will sound a bit different due to the lack of the heavy paint job that the neon colored guitars had and the fact that the SK had a maple fretboard vrs the rosewood of the RB. I happen to really like maple fret boards. I always noticed a subtle difference in tone with my neon colored JEM guitars and all the other JEM guitars. I just figured it was the mammoth killer paintjob they did on the neon ones (if you have ever seen a neon colored guitar chipped you would see how thick the paint job is.) I would try out a RB first if at all possible. You might want to go for a neon colored JEM. Heck 2 JEM777DY's ended for right around $700 a piece on EBAY just a couple weeks back. A JEM777SK (pink one) ended for only $665 (way to score Aqquake!) on 07-04-03. The prices on the neon colored JEM's has definitely been dropping lately.