You know, I've been debating this myself for a while though I don't seem to have the kind of $$$ you do
Bottom line, with any projector, you'll never get the resolution you would out of a HDTV but projection is more about size than picture resolution.
The next debate is LCD vs DLP. Pushers of DLP claim the blacks are better. What I've found with DLP's is since the technology uses colour wheels, if you move your head quickly, you kind of see a rainbow effect. This doesn't happen with LCD projectors and is extremely annoying when playing video games on the big screen

I've had a chance to try several projectors (from work) both with LCD and DLP technology and I'm leaning towards LCD.
Finally, the big debate, is the monitor or the sound most important? Both go hand in hand. If you have big sound, a small picture is very disappointing! The same is true with a large picture and small sound. Thankfully, you can now achieve a very good picture with relatively inexpensive projectors. Any of the new $1000-2500 projectors, IMHO, are as good as the $4000 ones.
So, with all that said, I'd go with a cheaper projector with a decent screen, achieve the big picture part of the equation and then concentrate in matching it with the complimentary big sound.
JB