09-26-12: Br3098
Exposure to extremely low temperatures will almost always cause a weakening of the structural integrity for most metals and alloys. One of the guys I went to school with worked for NASA and NAA on the Space Shuttle project, and later on the initial planning for the ISS. Anyone who believes that cryo is universally good for any commercial metal structure should read some of the white papers and technical information that is available to the public.
I understand your position and in some cases I can verify your statement is true. In other cases not.
The worst result from cryo came with treating tightly wound transformers, both large (amps or speakers) and tiny (MC Cartridges). After ruining several pieces we concluded that the transformer had no room to "compact itself" when shrinkage occurred at super low temperature. This caused fractures to the wire and even after lengthy break in times the damage seemed to be irreversible.
On the other hand, what Geoffkait claims is also true. I sell electrical outlets that are cryo treated and it does help the sound. If the cost is low enough to be worth the benefit I see no harm. Especially product that appears after many years experimentation to suffer absolutely no harm.
Precisely on this topic, my experience with cryo tubes are that they sound the same or worse. I have (unfortunately) not been successful with cryo versions. Then again, I suspect the tube type, tube design, circuit it's used in, personal taste and other factors all play a role.