716p's Vs. Fancy Caps

Being as the 716p's are film and foil polypropylene with copper leads I wonder why they tend to get a bad rap for Hi-Fi (besides the fact that their ugly and inexpensive).

I've used my fair share of $10-$20 coupling caps and they sound good. But I have not done extensive back-to-back comparisons in identical setups. Capacitor signatures are a matter of preference, but has any one found the 716p's to be sonically inferior for Hi-Fi?
Along with the 716P series Orange Drops, Panasonic ECQ-P(U) series caps. are price/performance champions. Inside a NFB loop, with its homogenization, there is (IMO) little reason to use anything more costly. ECQ-P(U)s are constructed of polypropylene film and Aluminum foil. The leads are Oxygen free Copper. That's a lot of cap. for very little money.

Snobbery is the only logical reason these good performers are not more popular. ;)

I agree with Jim McShane that mixing dielectric types up is, in general, a good idea. AFAIK, hearing the amp, not a particular dielectric, is the object of the exercise.

PIO caps. outside a NFB loop? Certainly. You actually have a chance of hearing their contrbution to the overall sound. :D