I see you are a master of understatement.
Nah, just a speed freak. I've liked Koopman fast organ playing in almost all cases, especially in large toccatas or in the Leipzig chorales (which are great fun to listen to). I think the only ones I've disliked are his Bruhns and Buxtehude magnificat primi toni (Like Piet Kee the most).
But again, I do like slower performances so I can hear more nuances. But some, like Walcha, sound too dry and neo-baroquey to me.
I listened to Rubsam, and while the prelude was a bit too heavy for my taste, the fugue was nice and grand, and indeed highlighted the dissonances well. But not earth-shattering.
What's the organ used in the recording? Naxos' website is rather hard to navigate. It's definitely not the rococo-southern-german instrument on the cover - it sounds like a Northern or possibly central German instrument. From the mixtures, is it Groningen?
Edit: it is the Martinikerk Groningen.
Another edit: Found a version I really loved, played by Dirksen. I think I enjoy it more than Winsemius who plays on the same organ.https://www.youtube.com/watch?v=zMN_O932v8Y
Edit #3: I found a description of this piece on Contrembombarde, which I sometimes visit. Quite interesting:
Dr. Albert Schweitzer saw in the prelude the vision of a "crowd moving along in solemn jubilation; Harvey Grace, and others have pointed out the thematic resemblances to the opening chorus of the Epiphany Cantata, "Sie werden aus Saba alle kommen," but that cantata was composed some 20 years earlier. E. Power Biggs thought the "carillon like" pedal part in the prelude "radiated the festive lights of Christmas," while Anton Heiller felt that this piece was about the Resurrection and Ascension.
The fugue is outstanding for the terseness of its distinctive subject, the tautness with which the fabric is consistently woven, the dramatic force of the long-delayed pedal entrance, and the well-nigh superhuman strength of the torrential flow of sheer energy which is guided, and, at the end, curbed, and all while sitting upon a long and triumphant tonic pedal. (some of these notes are from the writings of R. D. Darrell.)
Edit #4 (Oh dear):
I'm listening to Koopman's Buxtehude Magnificat I mentioned earlier- I'm enjoying the speed, but sometimes I wonder if Koopman uses speed as a "mask" to hide under when he doesn't have any other insights to offer about a piece - after all, speeding a piece up is a surefire way to make it sound "bold and refreshing."
I think the true masters are the ones who are able to slow things down and make it sound good. Like Leonhardt, Rannou's Goldberg, Glenn Gould (Okay, he sped up everything else but some of his "slow" ones are pure genius), or more recently Wim Winters and his Partitas.