Re: bubinga stripes and one piece maple necks
I haven't gotten to A/B the one peice and three peice 7620 necks, but I can make the following observations from personal experience:
1.) I prefer the looks of the three peice necks - if playability is the same, I'd prefer one of those.
2.) By the book, the original RG7 neck and the UV neck are identical, as measured by width, nut thickness, and thickness at 12th fret. However, my old-style one-peice UV neck ('891 UV7PWH) has a much smoother curve to it's profile than the '99 RG7620 I also own - the UV's neck is more of a smooth C, while the taper on the RG7 is a sharper D. Also, the frets are different - the RG has jumbo frets, while the UV's are medium. Between these factors, the UV seems to "feel" thinner, but a visual check seems to suggest that they're identical thickness. So keep in mind when comparing different models that profile and fretwire can affect the feel of a neck as much if not more than it's thickness - I believe most Ibanez seven string necks are 19mm at the nut and 21 at the 12th fret.
3.) I'm also not a fan of super-thin necks - I had some wrist problems from the Wizard neck of the RG-520QS I sold to cover my 7620. Beautiful guitar, but the neck was just too thin for me to be comfortable, and a bout of tendonitis was the result. Although, it's worth saying that it really made me focus on cleaning up my playing posture, and maybe the thinner neck wouldn't be a problem these days.