funny thing is, the VG series doesn't use MIDI conversion to make sounds (it is available on the 99, but that's a bonus feature)
it's doing it all through hex processing.

While the whole polyphonic-aware processing (even Roland does it in the SY-300) has come a long way, there still are limits -- it's closer to Roland's paraphonic processing (a rolandese term for dealin with "oscillators" real or virtual, individually but then having filtering, etc being dealt with as one big mono signal)
so, for example slow-gearing an arpeggio (with each string/voice having it's own enevlope) isn't really an option currently

I've got a couple of Boss GP-10s, and they're the basis of my rigs. They'll do both guitar and amp modelling via hex pickup (I use a Godin XTSA) but can also serve as an amp/effects modeller with a regular guitar. They fact that they can do both is what I need, and probably 90% of the time I'm using them as guitar (and now Alto Stick) processors. Also, there's a one-man Swedish company called Primova Sound that makes an add-on box called the MIDX-20 that enables a GP-10 to output MIDI. I use it to run Reason soft-synths from the Godin.

The gp10 can output to midi. Just check the manual.

I own both the gp10 and vg99. The vg does a lot more, but it's super pricey, even used still goes for a fair amount. Then you need a floor controller. the combination makes it bulky to use and more comlicated to set up. The gp10 covers a large percent of the VG, in a small unit. I like both, but the gp10 has become my default unit.