Ran across this article. The subject is the impact on dielectric "soakage" in capacitors on hold-release circuits. Soakage is the tendency of the dielectric material to hold voltage. In a nutshell, the article suggests that (among others) polypropylene film caps have better performance for this metric. I'd suggest that this affect may be a good physical explanation behind some folks' preference for capacitors of one dielectric material over another in audio circuits.