I ended up getting the PA75U a week or so ago. I opted for that one instead of the PA70G. Got it from newegg for $650. It has way more features and supports most all 3d formats instead of the PA70G only supporting 3d from PC. Also the PA75U has a few smart TV features and a digital TV tuner. I'm pretty happy with it. I was going for a cheap home theater so it worked out perfectly, plus I wanted the option of having 3D that would work with Blue Ray players and other devices.
I've not had a chance to try out the 3D yet cause I ordered my glasses directly through Sainsonic, but am still waiting for them to arrive. Takes a bit of time to go from China to the US through USPS. If I would have known it was going to take this long, I would have ordered from somewhere else, or chose a different shipping method to get them here.
As far as picture quality, I'm impressed. on 720p and 1080p modes, there are also all kinds of other video/color advanced options to fully tweak the picture. It also has a picture setup wizard that's pretty nice for getting the colors, contrast, saturation, etc adjusted. Not sure why they didn't have those advanced functions available for the native resolution of 1280x800.
So far, I've not noticed any rainbow effects at all. Colors are extremely vibrant, and blacks are pretty dark. I've not had any focus issues at all, and I have approx 113" diagonal screen. It does have a feature called tru-motion that I really don't care for. When enabled it makes movements in the video more fluid. It's a pretty neat feature, but I just don't like it.
It does not have a zoom feature, which was okay for me, but would really help someone to adjust the projected size to fit their screen. I actually used the screen calculator from projector central, then put my projector on a mount attached to a board in my drop ceiling, so I could adjust it forward and backward until I got the screen size I wanted. Then I built my screen based on that size.
What's funny is I was going to originally buy the PA70G, but came across the PA75U on some reviews. I couldn't find it on LG's website anywhere when I was researching projectors. Now it's there on LG's website.