I have experience with several varieties of ultrasonic cleaning equipment and Aggi and Thilo are correct. They will remove practically all the emulsion and anything else from your 4x5 leaving you with the clearest film ever (probably, depends on the power of the device).
The working theory in developer agitation is two fold: 1. to remove the layer of spent chemicals and 2. to replace with fresh chemicals. The theory of ultrasonic cleaning is to jiggle the subject in order to physically shake off adhering particulate. These are diametrically opposed mechanisms. The bottom line is: donít bother. Normal agitation is better.