There is a lengthy review of the Optoma Movietime at avsforums. It appears to me picture quality is comparable to the SP4805. Unless your budget won't allow it, I would recommend looking at 720p projectors and not 480p projectors.
I got it for under $2200 from a local brick and mortar chain, pm me if you want details. It's only under $2k after the rebate. Plus now with the rebate you get 'up to' $300 in rentals from blockbuster.
you can get a Z2 from projectorpeople.com for $999 shipped which is a 720P projector
you can also get an H31 which a 480P with screen from costco for 1249
it's all a matter of what the viewer sees but based on my research the 480P H31 seems to be regarded better than the 720P sanyo especially for dvd's (my own primary interest)
if you are going to watch the a lot of hi def and sports perhaps the Z2 is a better choice