Just to chime in here,
I got really enthused about Midi guitar and the possibility of playing other synth modules etc. I went out and got a bunch of midi guitar gear - starting with the Axon 100, then a Roland GR-33. I drove them with a GK-2A on a Strat. I wasn't happy with any of it, but the promise of the technology kept me interested. I bought a Roland Ready Strat (NOT a good guitar BTW - for some reason they chose to throw that technology into MIM Strats that are really closer to Squires. Every fret was sharp as hell on the ends and the normal guitar sounds were very cheesy. Even the GK didnt track particularly well, despite tons of adjustment.)
Then they came out with the GK-55, and both Wechter and Godin had some higher end 15 pin guitars with piezo/midi pups in the bridges. And Graph-Tech came out with the Ghost Saddles that are Piezo and Midi. Yes I bought them all. The GK-55 is a real improvement. It is much closer to where I thought they would be, despite one of the worst user interfaces I have ever encountered. The Godin and the Wechter are similar guitars, both play nicely, are useable electrics if you want humbucker tone, and the midi pickups track reasonably well. But - you really need to work with them - they are VERY playing style sensitive and you need to adjust your playing for the patch. Some patches track much better than others. Some require you to damp to quiet muted strings, and some just dont track right at all. I wanted to play the Cake song "Short Skirt, Long Jacket" in a quick cover thing I did last summer, and figured I would use the GR-55 for the trumpet parts. I did it - it came across OK, but I had to focus so much on picking and making sure each note was demonstrative. Hammer ons and pull offs are not always read correctly - (and yes I have it set up correctly).
So yes these devices have improved. But they still have a way to go before I would play them on a stage in a GB band or a cover band and try to rely on them as a keys replacement. Some synth pads maybe. I was hoping for a B3 sound that worked - not so much. And as far as 3rd party plugins or synth modules go, their voices are not designed to be used with a Midi guitar. The velocity and sustain are hard to capture. How do you keep a synth pad going after the guitar tone dies? Yes you can tell the synth to hold it with a pedal, but its not the same.
However, to the user who implied MIDI was dead, and then pointed out Keith MacMillan's company among others. Ironically, Keith McMillan makes the leading Midi aftermarket pedal, the SoftStep. They are trying other protocols, but MIDI isn't going away. I have the current Yamaha Motif XF8, their flagship synthesizer, and they have a full MIDI implementation and are developing new products in IOS to use Midi, etc. Midi is alive and well and frankly a pretty robust protocol in many ways. Mini_Amp Gizmos are very cool little devices to switch channels on a non-midi amp. I have them for a couple of Mesa amps I have and they work great.
I understand the OP was just saying that the VG-99 and the Axe II are a great match. In a controlled, one track at a time situation I agree wholeheartedly. It is just my humble opinion that the technology isn't really ready for primetime playing yet. Playing live with those devices would be rough. Maybe I am just old and set in my ways, but I would love to actually see someone using a VG-99 or a GR-55 fluidly in a live show. Just my $.02
Joe