Improvising with Bach Chorales

I remember reading a story at some point or other about a visitor [Update: a correspondent informs me that this was Jean Langlais] to La Trinite in Paris. At the visitor's arrival, Messiaen was playing, and the visitor, astounded at the extraordinary beauty of what he was hearing, inquired afterwards as to what the piece was. Turns out, Messiaen was playing a Bach chorale at an incredibly slow tempo, and this completely transformed the piece.

I have always wondered what this would actually sound like but never tried it. Until today. My communion "improvisation" (and in many ways this sort of thing is indeed an improvisation) was Bach's setting of Liebster Jesu, wir sind hier from the Orgelbuechlein, played at roughly 60 b.p.m. to the 32nd note. (I estimate.) Musician readers, you must try this at once; the effect was quite thrilling.

Such a drastic shift in tempo allows, even necessitates, a change in texture, so I used the following registration:

Swell: 8' string; voix celeste; 8' flute; 16' bourdon
Pedal: soft 16' and 32'
Swell coupled to pedal
Swell box closed

Try this! It is quite ethereal.

Now, if you'll excuse me, I must run from the 4' Spitz Prinzipal-wielding mob which is chasing me down.