I have owned 3 Optoma projectors and one sure thing I have noticed is that their specs for lumens and contrast are largely exaggerated in most cases as compared to the industry standards. 2400 lumens is probably close, but 500K contrast I seriously doubt. I have a 142x now and no way is it at the specs they say. Read the reviews/tests before you buy any Optoma product to know what specs you are really getting.
JCP. Benq HT3050, 120" DaLite, Pioneer Elite SC-LX501, Klipsch Heresy fronts and backs, Infinity center, Klipsch KG-2 sides, Velodyne HGS 18" sub, Paradigm PW2200 sub, Triad PowerSub 18", Energy 15" sub. Panasonic BDT-310 & Sony BDP-S790 Blu-Rays.