I thought I would add to this thread.
I currently own the Degritter Mark II. I have also owned and gone through 4 Audio Desk machines.
Ultrasonic cleaning does reveal more from the grooves, there is no doubt about that. However, for most of my used record purchases, I first clean the record using a Spinclean. That removes the larger crud off the record. I then follow it up with a 3 step fluid cleaning (distilled water, enzyme cleaner, purified water final wash) on a VPI 16.5 vacuum cleaning machine. Then the final clean on through the degritter.
The records come out pristine and there is a further purity / clarity in the sound. Labor intensive, but worth the trouble for a better listening experience.
Though the Audiodesk machines have improved over many iterations, they tend to break down over time and since their design isn't modular, you have to replace the whole machine. I did so 4 times and just gave up.
I bought a Degritter Mark 1. 10 months into ownership, some issue developed with a valve. Degritter paid for a prepaid shipping box, the machine went back to Finland, and they shipped me a brand new Mark II machine. Not a single penny out of my pocket. A great end user experience for me.
The other option is the KL Audio which had outstanding build quality. It cleans just as well as the Degritter. Onky issue is that it is louder when cleaning, which can be annoying. It is also more expensive.
Hope this helps somewhat.