No way!
Leave the 7 to Petrucci.
Well, it has nothing to do with skill or ability really (if you heard me play, you'd know), it's just a question of adjusting to the extra string. I'm sure no bass player would think that it's any more difficult to play on a 5-string than on a 4-string. If anything, it's easier, as you have more notes at your disposal within a single position.Pablo, I admire your ability - I have enough trouble with six strings.
It is the main drawback with signature guitars - options are limited to what the player who puts his name to the guitar agrees to.
I'd love to see a Morse with maple or ebony as a fretboard but it's not gonna happen unless Steve says so.
We can all dream...