Well, for what it's worth, the Dayton's I've tested came in well within spec, and that's for the regular, not the 1%. In most cases the value was spot on to two decimal places. I was surprised.
With capacitors, I would argue that better manuf. tolerances and materials means a better overall sound and more importantly, the value will stay the same over time (a big reason to avoid electrolytics).
That all being said, I can't see how the Jantzen Z-Silver is worth over 10x comparable alternatives. It definitely won't sound 10x better. At that point, your money would be better spent on better drivers that needed fewer crossover components!
