The first/only "don't care" vote is from me.
It's not that I don't think it matters, I just don't think the pros/cons for either seriously outweigh the other.
Yes, it slows down the game. The game will still be insanely fast and if it's not fast enough, play more tables.
I think HUDs probably increase the edge that regs can achieve but does mean that they can't play completely exploitive poker and have to take a slightly more balanced approach. I think it's too early to tell if this will overall negativelly or positively effect the people trying to make money off of rush.