What are you missing from the SY1000 from the 1/4" input?
I haven't yet tried a GT1000 or VG-800. From demos and what I've read though, the GM-800 wouldn't offer much over the SY1000 for 1/4" use apart from the built-in FX Loops and some added amp modeling while you lose some of the modeled synth abilities (like the Dynamic Synth engine) that the SY-1000 has. For me the Dynamic Synth engine is a big part of what makes the SY-1000 so cool due to the lack of any latency and the flexibility of layering multiple sounds- very different than the triggered synth sounds in the GM-800, and can be triggered from the 1/4" input (which I don't believe is an option for the VG800 synths, though I could be wrong)
Thanks for getting back to me. I need to spend more time with the SY1000, but so far, using it as a preamp and effects for bass isn't a clear winner over my pedalboard and the VG800 might be a better companion to the GM800 from a GK equipped guitar.
The VG800 and GT1000/GT1000 Core are said to have newer modeling options and a greater number of amps for the 1/4 input, so I'm planning to try those next.