I suppose I have probably had significant "experience" with a guitar synth, however, it is not broad.
I have had a Roland GR-50 since 1993, and I really enjoy it. It is not for everybody, and you have to expect some compromise between it and a keyboard synth.
Tracking can be the biggest issue. I always had problems with
my GK-2A, and its mounting on my guitars. I had it permanently mounted on a BC Rich, but it was still temperamental. I found the string spacing was not correct for the hex pickup.
I had the unit in storage for 4 years while in Tokyo, then upon my return I pulled it out and started playing with it again. Again, I was not happy with the GK-2 and did NOT want to mount it permanently on my Tele, so when I found a used
Godin LGX-SA, I bought it.
Best thing I ever did - now, the only thing that bugs me is my technique. I really notice it when I'm sloppy. There is also latency due to sampling, but if it gets too bad, I can slide it over in the mix. God, I love software.
Sounds, well, it all depends what you are looking for. You can use the GR-50 to trigger via MIDI anything you want, so the sky's the limit. If you're comfortable with the guitar, rather than the keyboard (like me), it's a great MIDI controller. I find the guitar much better for controlling patches like wind instruments and strings
, you can better approximate the instrument.
It will track a fast riff, but only if you are VERY clean - if you mess up, you'll get squeaks and squawks and all sorts of weird shit.
I saw Pat Metheny playing a GR-50 back in 92, he was using his Ibanez, with a built in hex pickup. He was controlling that thing like nobody's business, so it can be done. You just gotta work at it. Personally, I would not particularily want to play it live.
I would say I'm between both your comments - it's a great tool for me, I do use it, but it does have some limitations.
The GR-50 is a great box, though - used, you probably won't find a better deal. Single space rack mount. Just wish I had more time to play with it though.
Hope I gave you an idea, anyway.
Cheers,
Mike