For a home theater what would be better in a projector, a high contrast ratio or a high luminosity?

Here's a projectors I've been looking at: ViewSonic PJ755D.
The contrast ratio is 2000:1 and the Lumens are 2700.

I've also been looking at the next one in ViewSonic's line: ViewSonic PJ862.
ANSI Lumens: 3100, Contrast Ratio 400:1.

I want a projector that I can still see in the light, but also has good detail and quality.

I've heard arguments either way as far as what's better, a high contrast ratio or high lumens. Is it true that, unless you're in a light controlled room (pitch black), anything above a 400:1 ratio is trivial?