No fight! Simply a presentation of different views about Ultrasound - none backed up with Ultrasound data - because it seems no one has bothered to test for the use case "sound", "intonation" or "response". I never said that it was bad or good, I simply raised some logical questions that no one has yet been able to address.
The spectral information about changes in the "sound" of specific well played trumpets vs. a little played control instrument only serves to show that the much played trumpet changes spectrally with age in spite of good maintenance habits. I believe that this is due to changes in the stress patterns in the metal caused by the vibration of playing as well as the mechanical act of holding the instrument. I am sure that a day in a hot or freezing trunk also plays a role in the aging of the brass.
None of these instruments have been or will be ultrasounded. I have zero experience with trumpets and ultrasound. I do have my wifes ruined glasses and the firsthand knowledge that Mercedes and Volkswagen had serious issues with ultrasounded fuel injector nozzles failing (only the ultrasounded ones). I also have firsthand knowledge about ultrasound and precision tools (where a "depends" is quantified!).
None of this necessarily needs to apply to the devices sold for musical instruments used in a predefined way. If the techs have never asked the question, how do we know? What is that predefined way? When does it make sense to not use ultrasound instead of chemical or mechanical means - the only resounding answer in this thread was: when it is financially worth it.
I know of no collection of data on things like failed solder joints, temper, sound(timbre), intonation, response or anything else. In fact, I only know of a couple of places in a position to objectively test for this type of change: Smith-Watkins and the Institute Wiener Klangstyl for instance.
Think about this: how long are the cryo threads?, what about gap?, what about dark sound? Why are those threads so long? Because those that have experimented and those that have not feel a need to say something - whether the experimentation was bad or the "hunch was good", take a side..........
I am sorry if the only qualified response in this thread "no one has complained yet" is not good enough for me. I am sorry if someone feels that my questions may endanger their investment. Just use my response as something to consider. In real life it may be "good enough".