I replaced the stock pads on my Pro 80s with a set of SRH940 pads, fit and feel are excellent. Not as big a step up from my broken-in HI2050 pads as I was expecting in terms of how the velour feels, but the SRH940 pads start out soft, while the HI2050 pads took a little time to get there. The 940 pads have a thicker material covering the cup opening than the Pro 80 pads, but without A-Bing I didn't notice a drop off in the highs. As Claus mentions a few pages back, switching from pleather to velour pads has the predictable effect on SQ - bass is slightly reduced due to the loss of seal around the ear, and sound stage increases. Still plenty of bass, and decidedly less claustrophobic, while still eliminating the sound leakage from open headphones that wakes up the Missus whenever I get a missile lock playing Battlefield 3 (it's a rather high-pitched whine that can fill a room when using the HI2050s).
The 940 pads also leave a bit more room inside the earcup for my ears. While I haven't had a ton of head-time with the stock pads on the Pro 80s yet and they (or perhaps my ears) would have no doubt broken in nicely given the chance, I've just been spoiled by the comfort of the HI2050s and didn't care to wait.
Shure HPAEC940 Replacement Velour Ear Pads for SRH940
I'm also planning to swap the Pro 80 pads onto the HI2050s to get an idea of the tradeoffs to soundstage and bass. If it goes well (or maybe just for giggles), I'll order the Brainwavz HM5 pads (or an equivalent, since there are numerous rebrands of that headphone too, and while I hear the Fischer ones are the best I haven't found a source for just the pads).
Brainwavz HM5 Spare Earpad 1pc