My Epson Cinema Pro 800 is rated at up to 1600 lumens. It does a great job starting at 10 to 15 minutes after sunset on a street with house lights. My recomendation based on personal experience is to go with an Epson, I like the fact that the 400/800/810/1080 all have lens shift and a 1.4 -2x zoom this makes setup easy. I also like the reliability, warranty, and great design features that make them a joy to use.
I had asked for recomendations on a projector for my sons school that would like to do the same thing 1080p is not as important to them. You may want to think about a second projector as the mounting and un mountinng of a projector can be a bit of a pain. Here are the responses that I got in the other thread:
Epson 400 $9?? with the $500 rebate
Epson 800 or 810 around $1600
Check out the Mitsubishi HC1500. It's a DLP, so placement isn't as flexible though.
The HC1500 has been tested at almost 2000 lumens by art at projectoreviews.com
It can be had for under $900.
Unless they're in a rush to purchase, you might tell them to hold off a month or so for the new Epson Moviemate 72. From the pre-release info, it looks like an HC400 with a built in DVD player. Same brightness, zoom, and lens shift as the 400. Having one less piece of gear for outdoor setups would seem to me a real plus.
The Optoma Ep1690 is 2500 lumens $1000