hm, I haven't read the pre-Lindelof script, but heard about the Holloway scene - don't know what to think of it...
Two "Aliens" wrecking havok would be a little crazy - on the other hand, if the engineer and the "Xeno" ran amok, only to be drawn togehter (Oops AvP!), that could have been awesome ;-)
Hope we don't have to wait another 10+ years before "part 2" comes out - I'm also very interested in Ridley's "Blade Runner 2" - need to read the books though, I got all of them, but so far only read "Do androids dream of electronic sheep" - kind of an eye opener, like all of P. K. Dick's stories, and totally different to what we got on film...