Oh gosh I might trade away my Jem
Dude, do it immediately... *I have 3 JPMs (2 EBMM and 1 Ibanez) and a 7VWH. *I find the same thing that you've found, the 7V doesn't want to do really crunchy metal rhythm power chords. *The individual notes sing instead of distorting which makes the guitar sound very un-metal (at least through a tube amp through a Line 6 it probably doesn't make a difference).
I recommend getting a plain vanilla EBMM JPM with no options. *It's a great guitar and will give you the rhythm sound you want directly out of the box, at least it did for me. *The same can be said for the Ibanez JPM in comparison to the 7VWH. *Also if you ever want to play 7, consider getting a plain vanilla 7. *They sound even better than the 6.
As to the question of sounding like Petrucci, if you want to have his tone you can do it with a JPM and the least expensive Mesa amp that's currently in production (probably the F-50 if you want a new amp, otherwise the Subway Rocket). *As for playing like Petrucci, I have to go with what DaveSwift said. *In any case, even if you can't play like him (which I sure as hell can't) the EBMM JPM works great for all of your standard metal duties like Maiden, Queensryche, Metallica, Megadeth, etc... *In my opinion the same can't be said of the 7VWH running directly into a tube amp.
For Petrucci's lead tone, his pop comes from his incredible technique as well as using .10 gauge strings and probably 2nd behind technique is Mesa amplification. *Mesa amps have TONS of separation between notes even with lots of gain. *This is common to many tube amps though. *I find that the 7VWH is more than adequate for playing Petrucci style leads. *In fact I learned a lot of Scenes from a Memory playing my 7VWH and it sounded great on the lead work. *I just found it a bit lacking for the Metallica sound rhythm stuff.
(Edited by lgascoig at 10:18 am on Mar. 29, 2002)