According to the Dayton website they're still Film & Foil. I doubt you'll get much consensus on the value of small shunt / bypass caps though. 😉 For whatever it's worth (nothing) I'm generally unconvinced, although they do seem to have some influence in the JBL setting; since many of the speakers in question are big HE setups with compression mid-tweets, horn HF etc. we're not dealing with a regular low efficiency cone & dome set of conditions. YMMV as always.