I have one of the GK2ah's on a Telecaster that I use for this.

To answer some of the Q's. They do not make a 12 string pu only 6 and for bass.

I use the GR20 interface from Roland and it works great. It's not the only game in town though Axon also makes a higher end setup.

The setup, which in fact does convert the signal to midi works great when dialed in for single notes and better on some instruments than others.

It does not work as well for chording or styles. Here's why ..... think about how a guitar chord is actually strumed, i.e. a note at a time. So what happens is the pickup reads it as such and changes the chords / notes accordingly.

Example 1st position open G strummed it plays G>B>D>G>B>G that's what the midi module will do as well change chords for each note.

Terry