Have you considered the Infocus sp8602 or the new Mits hc7800 with a 6x color wheel. I am RBE sensitive but at 6x we shouldn't see them very much if at all. Even the new cheap Optoma hd33/3300 DLP's have 6x color wheels now. I don't think those RUNCO's can quite get to the LCOS black levels if you are a black-level fanatic, but DLP's have other advantages as you probably already know.
You might be better off with the new JVC RS45 if you are just going for black levels.
To me I'd probably stick with 1080p mainly because of the pixel-fill ratio is higher creating a smoother image, but I guess it depends on your own tastes of course. I think the pixel fill ratio actually helps more than just the resolution increasing, of course depending on how close you like to sit to the screen.
Not sure where you live, but if you really want to see one that bad, you can get airline tickets pretty cheap from some airlines if you buy them (15+) days in advance from a budget airline (jetblue, southwest, frontier, etc..). You MIGHT find a demo store somewhere. Star power in Dallas might have one in the back, but I doubt they have one on current demo (they have one Runco I think on display somewhere, or was that the place in Denver, something like that).