Hello David
One thing that is really brilliant about the Ahlborn units is that you can set the menu to temperament and then during a recital switch from Meantone to equal with one touch of a button
With Hauptwerk, it's a mouse click - though this could be a piston (etc) since most functions can be MIDI controlled.
My "upcoming" (I hate that word but it's useful) project is to set up a good portable instrument(s) for concerts outside, as I know some brass players who want to do brass and organ outside, as well as the opportunity to do concerts in places that don't traditionally have organs, as well as possibly taking an instrument into schools to introduce people who otherwise have no contact with organs to the instrument.
Is this not the ideal project for you to "take the plunge" with Hauptwerk? Two (or more!) MIDI keyboards on a stand, plus a MIDI-fied pedal board, a computer - could be a laptop - with a good soundcard and a touchscreen, and you could have the basis of a really impressive instrument - far more impressive to school children, I would suggest, than older electronic organ technology, especially as it would be based on a type of machines they are very familiar with. If you used MIDI controller keyboards, you would even have some buttons to use as ready-made pistons (though "real" pistons are easy to set up through MIDI anyway). The whole lot would be easy to set up, and of course you'd need the same sort of amps & speakers whatever is generating the sound.
Just a (perhaps rather cheeky) thought...
Regards
Ian