KeithAdv
BobF
...Other folks like Roland products or Godin (as mentioned above). I prefer the add-on because I can put it on any guitar (almost).
Well, to clarify what I was saying, I'm extremely happy that the Godin I have is a nice guitar even without the hex out, because these days I'm more inclined to run the humbuckers into a direct box and let the Midi Guitar 2 plugin handle the rest (Or just use any of my other guitars). The latency and tracking is the same, in my experience.
Technically, I don't think there's anything that will ever make the guitar as capable a MIDI controller as the keyboard. The technology makes it impossible to achieve 0 latency and 100% accuracy. (No bricks, please!) However, at some times it can be convenient to enter guitar-like phrases on the right instrument! I'm glad that I can address those times with software rather than hardware and play whatever guitar I like best.
I wasn't dogging the choice. Godin gets very high marks for their MIDI implementation(s). Very nice instruments. I ended up liking the MIDI keyboard well enough to start learning to actually play. I even ended up buying a Roland FA. So my TP does see long idle periods between uses. It's easier for me to get a reasonable sax out of the guitar, but for most things I don't see much advantage of one over the other.
The TP plug-in is really handy for layering VIs too. Works with any MIDI input, not just their controller.