I remember HoL HC (before or when PDK was released) being an ass - played my twink up and all were "so-so" geared - questitems, some blues, nothing like today. It was FUCKING hard. We wiped about 4-5 times - end boss with nova was the hardest off all.
I say - play WotLK HC with ppl with the usual gear and it will be hard, really hard.
Oh, and don't forget - WotLK at start was a way harder, then the gear got better, the skills changed, more theorycraft then ever before, the dungenon finder came in (hc with everyone in 185 blue = easy) and the players itself got better. The playstyle changed and the dps was going trough the roof.
Sad thing is, with ToC the gear started to get levels, the hc's weren't designed for. Same will happen with cata - now it's hard, but with the second or third tier gear, it will be easy again