This is interesting. I have two questions for you.
1. If Trey is finding that there is "nothing" wrong with the older networks that he is testing, why is he also offering to rework networks for people that he knows are "good"?
2. If you were offered two pairs of networks with the exact same circuitry, yet one had new capacitors that were of good quality and the same values as OEM, and the other pair was of the old oil can capacitors that were supposedly tested as good, which would you choose to install in your pair of (Belles)?
I can think of literally dozens of people (including myself) who have experienced much improved sound from their older vintage Belles, La Scalas, Khorns, Cornwalls, etc, etc, etc. after installing new good quality capacitors in their networks. And, those who supposedly test their old oil cans and pronounce them "good" are likely only testing for their capacitance value, and not ESR, or at the correct frequencies, with a proper tester. My perspective on this now, and always will be, if you don't try something new, you won't know what you are missing.