I am using one exactly like your ebay one. It has very kindly been lent to me by Utopia and Capo.
It works well. I only give it maximum of 15 minute bursts as the instructions recommend, to protect the machine. But you can repeat that ad nauseum until the parts are as clean as you desire. A bit of agitation with a brush between bursts helps with stubborn deposits. (Don't put your hands in when it's running though!) The more you can take apart before cleaning the better.
I do use it quite warm with the heater on, but the actual ultra-sounding does raise the temperature by itself. After about 30 minutes or less the heater can be turned off.
Do use the correct "carb and parts cleaner" though as lodger says. I tend to rinse the parts with clutch and brake cleaner after their bath, just to remove water and cleaner, so's it doesn't corrode them later.
Good luck with it, and if you can stay in the same room when it's running you're even deafer than me!
