According these reviews, there is a sonical difference.
I'm using the silver z-cap as input coupling cap in an amplifier, I don't notice any difference when bypassing it! (This could also mean my ears are not good enough, or that the rest of my equipment is not capable of making the dfferences notable.)
Humble Homemade Hifi - Cap Test
one has Siler other aluminum in its construction the tonal difference the silver is brighter than the aluminum they say in upper frequency range as far as ESR it is very little difference they behave almost identical in that respect MKP is polypropyle dielectric and is quickly becoming the standard vs MKT polyester few years back and the price gap is shrinkinghai,
is there a difference between Silver Z-Cap and Cross Cap capacitors both are MKP capacitors.