I've been playing my USA Curbow Int'l Petite 5 string with a high C for a couple of years now. I have never bothered to have the nut recut to accomodate the smaller gauges, and have never had a problem. When I had Curbow drop a new preamp in the bass, and set it up, I asked him if it needed a new nut. His response was, "If it isn't a problem, don't bother." So, you don't HAVE to have a new nut to try it out.
I've been using chords on the Curbow with the TI Jazz flats, and it sounds amazing. I never liked the jazz flats with a low B, but the chords sound crisp and clear. One of the nice benefits of the high C (besides solos and chords) is simply being able to play in positions without having to shift up the neck. Personally, I prefer the way a D sounds at the 14th fret on the C than the 19th fret of the G string.
Just thought I'd share my experiences that show a different perspective on some topics from this thread.
Oh, and a power chord is not a chord. Even if you play the octave. if I play an open E, 7th fret on the A string, and the 9th fret on the G string, I'm playing three different notes, but I'm not playing a chord. So, if you are playing the root, 5th, and octave, you are still playing a glorified doublestop, and not a chord.
I liked the GBass that I tried as much as I've liked any graphite necked bass. If you like it, you should be fine with it. Peavey basses have really improved over the years, and are still fairly cheap.
Good Luck with the high C. I love my bass set up that way, and you might be able to find your voice that way, too!