In the demo the dub is sounding pretty good. My only complaint so far is that Burton (of whom you all know I'm a pretty big fan of for Cloud) delivers "Burn" when Cloud casts Fire gratingly flat. But other than that things sound good, Newbern gets better and better as Sephiroth with each subsequent game in my opinion. "To the Promised Land" on Hell's Gate is really well delivered.
Searching for references, most of Cloud's and Sephiroth's seem to be from AC, hopefully they do get the FF7 ones down. I sacrificed myself with Cloud once, but he didn't use the "ain't no gettin' off this train..." line, but I dunno if there's more than one death phrase. I really hope they use that because that's pretty cool. They used it so much in VII but it hasn't shown up in the Compilation.
I wasn't sure about Terra at first but she's grown on me, I think it is pretty good. As for the new video, they got Bartz perfectly, I'm impressed, its a really good voice for him. I never actually noticed that he impersonated them in the Japanese version, I wonder how they did that...I guess they just played the other actors' soundbites and asked him to duplicate it.