Yeah, likewise. It makes sense with Dark Eldar sculpts and Dark Eldar sculpts only. No one else would want to sacrifice armor for hots.
I'm familiar with the scale difference, which is why I thought the heroic-scale heads would look great on either stock 40k Sisters or the Eisenkern Heavies. The Heavies are supposed to look like they're wearing heavy armor, but with the heroic scale heads on em I think they'd be a dead ringer for power armor. Now if only they'd get back in stock, or if Dreamforge would respond to the several attempts I've made to contact them... Seriously, I've had better customer service from people selling recasts than these guys. Unless I can get a deal like pretre posted, and hell even if I can, the Eisenkerns would be a lot more of an affordable option.