For a brief period of time I owned a Jem-BSB and a
Parker Fly Classic (and I currently have a VWH and a DBK), so I can give some perspective.
Cons of the Fly:
1. The Fly's neck is SO thin, that after long periods of playing my hand would cramp up. Could just be me.
2. For a guitar of that size/weight, the Fly has decent tone. But, to me, it still was somewhat like playing a piece of cardboard with piezos. It never had quite enough sustain and crunch for me.
3. The location of the upper strap pin drives me nuts... the body isn't thick enough to put dunlop straploks on (which would be poking into your chest if you did install them), and if you tilt the guitar at the wrong angle it's really easy to yank the strap right off.
Pros of the Fly:
1. The piezos are better, IMHO, than the piezos installed on the Ibanez double edge guitars. There's much more flexibility with switching and tone controls.
2. Though not a lo-pro edge, the tuning stability of the Parker trem, graphite nut, and
locking tuners is EXCELLENT.
Given a choice, I'd take a Jem any day of the week. Not necessarily because I'm a gigantic Vai fan or Ibanez freak, but just because the variety of tones are better suited for my style of playing.
Tip: Consider buying a used Parker... seems like they're always up on Harmony Central and e-bay. They're hard to resell, so you may be able to get a good deal.
--B