The easiest way to find a distributor is to go to the DOW website and request distributor information for your area. I haven’t found it for sell outside of a distributor yet.
In my testing of Yellow Magic 7, it worked ok in an ultrasonic cleaner. The specifics will depend on what ultrasonic cleaner and resin you use. It is not compatible with the Form Wash and doesn’t work well with plain agitation anyway. We also have not tested material properties (tensile strength, elongation, etc.) when parts are washed with Yellow Magic 7.
As for a comparison, the main differences are that TPM is considered non-flammable by GHS/OSHA (check your local regulations) and is compatible with the Form Wash. DPM will bubble the powder coat on the Form Wash.
DPM will dry a little faster, but way slower than even water. I have seen DPM on Amazon before, so it may be a little easier to procure.