I would need a longer period of time with the Thunderpants in a quiet listening environment to really get a good view on the sound. But again, I typically just don't like the sound of closed headphones. There are exceptions to that of the ones I've heard such as the T40v1... no, I think that's it for me, and the TP possibly could end up being another. Most orthos are closed-back but vented level with the magnets, which helps, and I usually damp the backs of the cups. It's not ideal, as absorbing the backwave completely would mean absolutely no comb filter effect/controlled backwave reflection, and typically whatever is used to damp doesn't damp all frequencies the same amount.
As to the price of the YH1000, I think it's mainly the rarity that keeps prices so high, though the aluminum cups and overall design seem to be quite good (and different from the lower end Yammy orthos). I liked the Don-modded LCD1 as well. Only things I remember it lacking soundwise were a bit of bass extension and soundstage.