Rec 709 is just a color standard for HD sources that, in simply speak, could be considered a reference that a calibrator tries to match when adjusting the three primaries colors. There are three different colors (red, green, blue) and they are all adjusted to accurately display the total grey scale between white and black.
If you really want to read up on calibration some, Calman (calmantv.com) has a great beginner’s tutorial. It takes a few reads, but after the second or third time, the pieces fall together.
Even though there isn’t a substantial difference between 720 and 1080 in regards to resolution, I’d still go 1080P over 720P. Marantz and Sim2 make phenomenal 720 projectors, but boy are they spendy…. +10,000. If you go 1080, you will be able to use 1080P/24 off BR/HD disks, which is quite a treat. Otherwise, you are stuck with a de-interlaced and downscaled image sourced from 1080i.
It’s hard to find actual data off these projectors. It’s out there though, just keep looking. A good source is some of the calibration forums. You can usually do a search on a particular projector and see what the pro’s are getting. Unfortunately, I think you’re out of luck finding much on the projectors you’re looking at. They’re too new.
Other things to be looking at is projector noise (noisy projectors are distracting), how much lens shift they have (both vertical and horizontal), whether they will V-stretch HD image in case you decide to with a scope screen, warrantee, cost of replacement bulbs (some are $600 and up)… and a few other things I’m not thinking of right now.
