I had this debate with a preamp/amp mfr who repeatedly stated to (screamed at) me that black gate capacitors required absolutely no break in, none whatsoever, and once a unit was warmed up would sound the same no matter what, period. He also told me that a cap that cost 1/10 the rpice would work just as well as the Black Gates, but i insisted on the Black Gates
I bought one of his units and he was right about the break in effects. There were none.
I bought a different piece of equipment from another mfg with the same Black Gates in it, and guess what: Huge break in effects.
Apparently how/where the capacitor is used in a circuit and the nature of the circuit itself can have an impact on how it affects the sound. But people don't talk about that very often, do they? Everything gets expressed as absolutes.