I have but I'm at the peak of a cold so impressions are off for now. Initially they're stiff and uncomfortable but after 4hrs or so they feel an improvement over hf velour and pleather.
Initial impressions seem to be better bass impact, with a slight boost in the lower frequencies. On first install there seem to be a slight bleed of mid bass to the mids but after awhile that has disappeared. Maybe the pads breaking in and being more conforming?
The presentation is more natural in a sense of depth and soundstage. You can get a sense of this by holding your hp at an angle to your ear with the back of the pad away from your head.
The mids and treble doesn't change with the pads. Just bass and presentation. I wouldn't say it's not worth the $40 in a sense of sound but there's quite a mark up on these pads from a material stand point imo. Maybe wait for hf it'll probably be in the $25 range but that's pure speculation. Fwiw, it took 10 days from date of order to me (West coast).
Intriguing... Warmer and more impact. I may have to get me a pair to try out! Thanks for the quick (whilst sick) impressions.