I had planned to place a 50-65" plasma on my media room wall for daytime sports and casual viewing and also have a motorized 130" front projector drop-down screen fall in front of the plasma for serious night-time viewing using a 1-chip 1st generation 1080p digital display.

Lately however, I have been wondering if I would be better advised to buy a super bright 3-chip 720P front projector and some near blackout drapes for the one (huge) window light source and just pass on the plasma.

Obviously, HD-DVD/Blu-Ray is the only sacrificed source material by choosing the 3-chip 720P route.

Any advice on this 3-chip 720P - vs. - 1-chip 1080P (and bag the plasma) alternative?

Unfortunately the image will look washed out even with a bright 3-chip. You will have to use a screen like DNP Supernova to get decent results, and since it's not optimal to use this screen in the dark you now have two screens (one dropdown in front of the other) instead of a plasma/projector combo. Also note that the Kodak 333 (if you're thinking about that one) is not superquiet...

Rear projection is an option but expensive. I would go for a plasma.

I personally do not think you will see much diifference between a 720 P and a 1080P projector because your eye only has a resoulution of 1 arcmin at the center and quickly drops down to 3 arc min off center and I have not included the color abberrations of the eye

a 3 chip projector will have no color wheel and will have better color saturation than a single chip. I own a single chip sim projector and although I do not see rainbows my eyes feel a strain as I watch a single chip. I do not feel this strain when I watch a 3 chip.

My Kodak is not that loud at all....

I would certainly invest in some curtains first ;)
I think it comes down to whether you are bothered/fatigued by rainbows. For the kind of size screen you are looking at, demo the Marantz VP11S1 and sim2 HT3000 and some 3 chip models. You could take a look at the HD81 as well but personally I would rater go 3 chip. As much as I like the high end 1080p single chip pjs, I am still uncomfortable with the technology. Picture-wise, the 3 chippers will be punchier but not as sharp as the 1080p models

the answer is how close to you expect to be sitting next to the screen, and how big of a screen are you going with. If you are sitting 2.0 times the width of the screen, resolution wont be a factor. If you are going with a small screen, the 3 chip may be to bright

For the sort of money you are talking about, whether you go for a single chip or a 3 chip, aspects like colour, optics, contrast etc. all tend to be excellent. After seeing high end projectors in a 2.35:1 setup, filling up your entire peripheral vision, I would highly recommend it. IMO the projectors that do this well, with enough lumens to drive a big screen, are the sim2 HT5000, HT3000, C3X, the Marantz VP11s1(brightness may be an issue) and Infocus 777. I think the deciding factors, when demoing, would be: whether you are happy with 720p pixel size in that kind of setup, which technology you prefer the picture of and will it be powerful enough to work at your place.