Well, I've been following this thread but haven't had a chance to chime. Alot has been covered, I just thought I'd share some of experience as I've used midi on stick for 8-9 years.
First, you had to adjust to midi because it will not adjust to you. I've used the roland gr-33 for a while and as with other processors, some patches just don't work well, grand piano, bells, sounds with more attack cause the midi to be more "glitchy". Just like you have to set action on the stick low, you have to make sure the midi pickups have the right spacing to the strings, this makes a big difference and they give you a tool to help measure the depth.
Last year I had dual midi installed on my grand and never looked back. The change has been phenomenal. The situation in one of the groups I play for is unique in that the stick is used for midi exclusively as back up synth. The set up is dual Roland GR-10s to a midi solutions 2 in 1 out box then to a korg triton and motif es rack. The full 12 strings go to the synths and I switch between them with volume pedals. I experimented with one synth on the bass side and the other on the melody but did away with this as I mostly use one sound at a given time, usually, strings, organ or pad.
I never had a problem with the location of the pick ups, in fact even though they are on opposite sides the 3-way switch is the same for both, down is "guitar", middle is "mix" and up is "GK". Also, I adapted the stereo monster cable to connect each side to the GKs. Red is bass, black melody. This is nice because it sends the bass and melody signals through the two 13 pin cables and out of the back the GR10s.
When it comes to midi on the bass side I've always had problems with the lowest octave, some times higher. The band has a bass player so I don't play low anyway. I've adjusted my playing to what they call "closed position" in piano instruction from "open position". As a keyboard player your much more familiar to this than I am but on the stick it means that I don't play the lowest 2 strings. I spend a lot of time on 10-12 on the bass side with the raised 4th tuning. The voicing and potential here is unlimited. Unless you are familiar with keyboard voicing you'd never know it's a stick vs a keyboard.
I think you would really enjoy dual midi. Like Kevin Keith, the compliment of dual midi to the tones on the stick is great. I'm able to play in 3 set ups, midi exclusive, club setting with guitar processor, gr-33 on melody and amps or just the acoustic image in a solo setting.