If $16, shipped, for a pair of earpads is "ouch", whatever you do, do not look toward Senn and AKG. Senn pads are generally $40-60 shipped for a pair and AKG runs $40-45 PER PAD, UNSHIPPED.
I don't know what Audio Technica charges but the lack of seeing them in the wild leads me to believe it's some exotic custom order thing.
HiFiMan has the cheapest pads around, anywhere.
How old were your HE500's? The early HE-500's shipped with a totally different earpad system that's been discontinued. The response to the original system resulted in yelling, screaming, and general disdain, and a lot of cracked pad rings.
The headphones I don't believe changed, just the pad assemblies. The old ones (with the older, thinner velour pad) had the old system with the big huge plastic tabs on the stiff, brittle ring. The new ones (new thicker velour and pleather) have the tiny wing tabs on a softer, bendable plastic ring. If your HE-500 was old enough your pad is the old style pad with the long tabs and the brittle ring (and the shallower, less padded velour.)
I would suspect that the neutral mids would lend themselves very well to atmosphere. The neutral mids may not be ideal for lots of dialogue in movies though. It would sound good, but may be harder to hear or require more effort than a mids-boosted lush can. Hard to argue soundstage though!