I got mine last week and I love them! I received the HD25 Adidas pleather pads this morning and I'm honestly disappointed. They feel very cheap compared to the stock pads, they're not as comfortable and they sound less open. I think the material isn't as good, the hole is too small, and the diffuser is too dense. It's a shame because they look very cool. Sorry Doc.
However I have bought a second jvc ha-s500 which will be arriving next month, and I'll be able to do a proper A/B, and likely leave the blue pads on one set just for looks, the sound and comfort difference isn't THAT big.
BTW I can't believe you guys still believe in burn in. Take your ha-s500 out of your drawer and enjoy them.