Re JS,,,, They are expensive and honestly I don't think they are worth the money. If you are looking around for a js satriani first think about an S model it has the same slim profile.
The S series was released at the same time as the original RG series. It has the same slim contoured body as a JS and the new ones have the new ball bearing trem system. Meaning longer life then the older knife edge system
I've had ibby's in the past and they weren't my cup of tea. Granted that was many many years ago. Nonetheless a lot of my friends on other forums have returned new ones due to a myriad of reasons.