Obviously a dedicated lead would be required for connection to the Roland 13 pin GK device you are using but the added confidence of having a good solid and reliable guitar connection is worth considering.

Next, there's the question of whether to install the S1/S2 (midi program change) buttons on the edge of the guitar as seen in the two photos above or, alternatively, we can install another 3-way switch on the front of the guitar which is 'centre sprung' - press one way for up and the other way for down - like the photo below (it's the switch to the right of the pickup selector switch):

If you like playing your guitar resting it on your thigh, the latter might be a good idea - but some people think it doesn't 'look' as nice.

Then there's the possiblity of doing away with the 'midi' volume control and the 3-way pickup switch (midi pickup only - midi pickup and humbuckers - humbuckers only) as seen in this installation. As you can see, it's a very neat installation - the midi volume is always 'full up' and the pickup selector is always set to 'both' - allowing the Roland pedal (eg VG88) to do the switching.