I meant to put in my two cents earlier, but I can state a few
principles:

(1) There is nothing wrong with adding a _reversible_ modification to
play MIDI (or whatever) on a roll/book/barrel playing instrument, since
the addition could be removed at any time and nobody could even tell
that the instrument was no longer a "virgin."

(2) It is a lot more _fun_ to watch a real roll or book go over a
tracker bar or a keyframe, and nothing beats watching a barrel pushing
fingers up and down.  So yes, MIDI is less fun to watch (and less
likely to keep observers interested), but it has its uses.

Background: I have published an article in the Carousel Organ Association
(COAA) Journal on punching one's own rolls for crank organs, and have
punched quite a few of my own tunes.  But also pending is a longer
article on how I built a MIDI interface (reversibly!) into my Raffin
31/84 organ.

So far I've used this interface to audition my arrangements before
investing the paper and hours of time to punch the piece.  My electronic
MIDI module gives a good approximation, but for the real test I want to
hear it on the organ, with me pulling stops.

I've not yet acquired the equipment to play the organ outside from
MIDI, and am not in much of a hurry, because Principle (2) above
applies to the public, including young parents who vaguely know what
a piano roll is, holding up their toddlers so they can see the roll.
I'd rather watch it too!  And they're so impressed with the work I've
done to cut the roll myself, whereas on seeing a computer they'd think
the computer did all the work (software, arranging, and programming
are way under-appreciated).

Totally different is my view about pianos.  If/when I get my Weber
grand Duo-Art playing again, I will probably MIDIfy it also, so I can
hear my own piano ragtime compositions played on a real piano.  Piano
rolls are not practical for me to punch, and I'd rather skip that step.
I won't feel guilty about "deflorating" an antique so I can hear piano
music on my piano.  Of course I'll still play rolls, as long as they
last (?)

Mike Knudsen