The ultrasound won't knock your socks off. It won't hurt a chemically-plated finish on reeds, tines, tonebar blocks, nor tonebars.
Ultrasonic cleaners do a very good job of removing grit and loose crud from fine-detail crevices.
The soapy solution used in the tank will remove grease and oil (and any rust-preventative oil as well).
Ultrasonic cleaners will NOT do any serious rust or corrosion removal. Just the loose stuff will fall off. It is a great way to get the remaining dusty crud off after wire-brushing or sanding a metal workpiece.
Sean