As I mentioned, for steel, cryo treatment has a pronounced effect - and a proven, well understood scientific explanation.
For other metals such as copper, tungsten, molybdenum - no effect at all. For these materials, there are no low temperature phase transitions and the other changes that some of the advertising points to (like "annealing" or grain growth) slow down exponentially as the temperature is lowered. If you want to affect the grain structure of these metals, heat is needed - not cold.
Rich