Other projectors
You might also check out the new Sanyo Z4 projector. Projectorcentral.com has lots of reviews on it and the new panasonic. I think they are both better options than the Sony and both are less than $2K from visualapex.com
For a dedicated room a fixed screen is the best option. However, it would be cool if the motorized screen came out of a slot in your angled ceiling. The key is that the screen has to be mounted so that the housing is in the correct vertical orientation. Weather on the ceiling or in the ceiling, this could be easily accomplished with metal or wood brackets.