What hardware options for the HEX version exists out there? The only thing I’ve seen mentioned is Boss GP-10…Also, what’s the AD conversion latency for these options? My RME interface is likely faster…but I miss playing chords with confidence 
I use the GK-3 with a direct cable I built myself into a Motu 828:
Ah, so there probably aren’t many solutions outside of the GP-10? A breakout cable + multichannel interface sounds like a good solution in the studio, but a bit too much for my occasional live use 
aside from the gp-10 there is also the sy-1000. both are kind of large for occasional use. also there is the issue of fidelity, the gk pickups filter the sound. this only affects analog output, but becomes more important as mg3 develops more analog sound processing options.
the graphtech and rmc pickups can also be used with the boss gear, as well as breakout cables. some guitarists object to piezos because of palm muting. their sound is also not ideal.
cycfi has a solution but i find it to be pricey. it is well designed though (i have one of their pickups on a bass guitar).
the subsix is an attractive option. $329 (but you need an audio interface). great sound, no palm muting issues. it is surface mounted so it does pickup noises (squeaky pots, for instance) which other pickups do not.
in terms of a/d latency, most of these options are in the high 20msec range. getting down closer to 20msec is possible with some audio interfaces (the pickup type doesn’t affect the latency).
I use a Boss GK5 pickup into a Boss GKC-DA to the Separate-Strings breakout cable to my audio interface. The GK5 is a digital output over a special TRS cable, but it very small on the guitar and I have the interface box on all of mine (3 guitars and 2 basses) mounted via the strap button on the back of the instrument for a clean install. These work very well for MG3 Hex. A little more expensive but much better results than SubSix solution.
what are the plusses of the gk5 over the subsix?
For me, The GK5 is more complex but way less intrusive to the instrument. The SubSix, while easy to move around with its sticky non-permanent pad install, is way bulkier and the cables are hard to route and deal with. And on most of the guitars I have, it wouldn’t even fit under the strings. You do need more hardware with the GK5 setup as you need the converter box and the GK to analog output breakout, but it works flawlessly for me. I have GK5s on my main 2 guitars with one waiting on a new Kiesel nylon AC2 build, as well as 2 5 string basses. Once you get the levels and gate dialed in, it is such a joy to play MIDI from them.
I actually had ordered and received a Rob O’Reiley MIDI Pro 3. It was a much better controller than any Roland or other pitch to MIDI system and the extra buttons were really great, but for me MG3 hex beat it hands down as an overall MIDI controller. I reluctantly returned it as I knew that MG3 would be the system I reached for 99 times out of 100.
Gil
have you used the subsix on any of the guitars you’re using with the gk5?
i was hoping more for ‘the highs/lows/??? sound better’ or comments on improved tracking/fewer ghost notes rather than that you prefer how it fits.
i think you’re saying you haven’t compared the subsix against the gk5 on the same guitar?
I couldn’t compare it on the same guitar as the SubSix would not fit under the strings. There wasn’t enough clearance on my main guitars. On the guitars it did fit on, the cables runs were too weird as they need to run to the top of the body and got in the way. I have since sold it and am very happy with my GK5 setup. I have no issues with balanced triggering or ghost notes once I get the levels on my interface set and the gate setting in MG3 dialed in. I find this to have extremely good dynamics from soft to loud, especially when playing keyboard/piano sounds with my fingers.
does the gk5 need power? if so, how have you arranged that?
one thing i don’t like about the gk’s is the mounting position, i prefer the string sound when the pickup is close to the neck. tucked away next to the bridge is a less opportune location in terms of capturing the guitar’s tone/nuance.
It gets power from the GKC converter. Since I am only using this for MIDI, I’m not concerned about the tone just that is clear and good level. I would assume the SubSix might be better for your application as long is you have the string clearance to mount it.