David, something I've never quite understood... why have you resorted to a rather Heath Robinsonesque arrangement of stopknobs, rocking tabs, double-touch buttons, Ahlborn units with buttons, etc, scattered all over the place? Why not just rebuild the console with bigger jambs and install the requisite stop knobs, etc?
The reason is twofold. Firstly, to accommodate around 200 drawknobs or even stoptabs in a conventional way is really unweildy and second, in practice, apart from compactness of presentation, the groupings of stops that the units afford make a deal of sense and they allow sideways couplings between flotational divisions beyond mere manual couplings. Normally the instrument is in a fairly fixed specification but at times it's helpful to put something somewhere on a different manual. This is particularly the case with the new section intended to provide Grande Tierce on pedals but in fact Jeremy Filsell used it to put a Tuba on the Echo rather than the Solo, as he needed the other four manuals.
Other complications arise with the versatility provided by the Viscount CM100, which is normally used just for Baroque Reeds. But from time to time, an organist will want a Gamba on Great, or as Jeremy Filsell did, more Strings to add to the mix. The device can give a dozen stops from a library of around 200 and can put them on any manual.
The octave couplers which work on the original instrument are interesting - they work on any of 10 channels carrying a variety of grouped stops. Not only is the Octave provided but if required, Sub Octave, Octave Quint and SuperOctave.
The instrument is not merely a playing concert instrument but is also a tonal "breadboard" allowing great flexibility of choice, permitting anything to be played, and also allowing trials of stop groupings possibly for consideration of pipe specifications.
Providing a conventional console arrangement would fix hard the specification in an unhelpful and limiting way. It makes it more of a sport for visiting organists to grapple with and more sparkle to the entertainment for the audience!