#1!!! DO NOT do carbs in a bath ANY bath unless you are removing the butterflies, throttle shafts and throttle shaft seals! Hot bath will trash the seals. Carb baths will trash the seals. You can do a great job cleaning carbs with mineral spirits in a spritz bottle and a tooth brush. then spray carb cleaner though the passageways and on stubborn deposits.
I have the "medium" HF USC, and have done many sets of carbs with the throttle shafts removed.. IMHO the heat does more than the ultrasonic but the ultra sonic does help. I use cheap walmart pine cleaner diluted 50/50 with water. Dump and change often. Don't let the carbs sit too long in the bath or you can blacken the casting, rinse and blow dry them.