I had the ml500. Just wasn't bright enough for me. I have a dual screen set up with a 100in SI 1.1 gain screen and a 119in da lite hp 2.4 gain screen. The only way for me to make the ml500 work for me is with a 80-92in hp screen or a matte white screen 84in or less. I like to watch tv with at least 25ftL. Anything less is unwatchable unless I'm in my main theater, because I have no lights and dark colors in there. I am still waiting on a 1080p led projector that is going to give me at least 800 lumens in best mode. The optoma gave me 385 lumens in brightness mode that were usable and 350 in best mode.
I wanted to get a Casio but I didn't want to pay that much that it was for the 1200x800 models. Personally, I would not get the optoma unless you get one for less than $450. I replaced my ml500 with a $400 acer h5360. Much better in my opinion