The real issue with US cleaners is the ultra high frequency vibrations imparted on your components.
This will cause finely fitted components to "fret" against each other. In extreme cases this can cause undue wear of those nicely fitted and precision honed components. Now add debris such as sand to the equation and you may as well be cleaning with a 220 grit orbital sander.
US cleaners are fine if you remember a couple of things:
1- rinse the majority of crud off first.
2- don't put assembled components in.
3- only clean the components long enough to get them clean, don't just toss things in for an hour.

Want proof? Toss a precision bearing in a US cleaner and let it sit there for an hour or two.