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I can't tell you anything about the ultrasonic process but like you I had a lot of records to clean so it started to make sense. It's not really a background process, although the more you pay the more automated and silenced it gets. It's noisy and you need a workstation where you can have it all going on. All those wet records have to drip somewhere and even the vacuum gets wet where water inevitably spills off the disk. So you got fluid bottles, towels, racks, brushes you need good light to see what you are doing, it's a crazy rabbit hole.
Is that really less hassle than the @>>>>>> method (I do it with washing up liquid and a soft brush) ? You have to measure and dilute the cleaning solution first, deal with the buzzing noise, still need a drying rack afterwards...