After an initial test in the last band rehearsal, I would now describe the changes as a complete success.
The Delano MM pickup is not quite as loud and therefore fits better with my other basses. So I don't have to adjust the volume every time I change. I also like the sound of the Delano much better, it sounds more open, 'airy'. The way it has to be. And as expected, the two single coils no longer make any noise. This swap alone would be a very significant improvement because it would allow the sound spectrum to be expanded and fully usable.
The SD Apollo in the neck position is terrific. The DM Model-J went clearly in the direction of a P-Bass and if you want to go in that direction, it is very good for that. To me, the SD Alpha sounds exactly like the Fender CS 60 (I have it too), just without the hum/noise. A very good vintage jazz bass tone, with a little bit more punch. More open, airy, almost 'three-dimensional', I can't think of a better term. I would say this SD Apollo fits the Delano absolutely perfect.
My preferred settings are SD Neck solo, SD Neck with MM Bridge coil, MM Neck solo, MM parallel and SD Neck with MM Neck coil.
For this tonal variety you usually need at least two basses.