Another new HD20 owner here. Upgrading from a Mits HC1500. I've only been able to play with it for an hour or two, but I've got to admit these projectors seem to be pretty buggy. I mean various other users have posted about strange issues when changing inputs/resolutions. We have people who get those lines across the screen etc.
For me when the resolution, or basically any setting like 16:9 to native changes, the colors get all messed up for a few seconds. Goes from green to pink and then everything goes back to normal. So not a huge deal, but concerning that the problem could get worse.
Another thing I noticed in just limited viewing without even looking for it, was a subtle flickering type effect on certain scenes in the couple BDs I popped in. I could only really notice it on aerial landscape type shots like the IMAX ones on Dark Knight and a few on the Incredible Hulk. Hard to describe but it seemed like the lighter areas in the shot were changing brightness ever so slightly. This is on 1080p 24hz with the PS3. I thought maybe it was the AI people were talking about earlier in the thread, but that is off by default.
I also have to say I didn't honestly know what a rainbow looked like with the HC1500, but I do now with the HD20. I went looking for them which was probably a mistake, but it wasn't too terrible so I'm hoping to "learn" not to see them over time.
The good news is I do think the blacks on this projector are a notch better than the HC1500, and of course the extra resolution is noticable (only watched BDs so far). Not as big a difference as I had hoped, especially when viewing on a 100" screen from ~12', but noticable none the less. The colors seem pretty similar out of the box. Haven't had anytime to do any tweaking or calibration either.
So all in all it's a mixed bag for me so far. I do not think I am a picky or highly discerning viewer, as I've only ever owned "budget" level A/V products and been very happy with them.
We'll see how things play out as I get more time with this projector. Hopefully these buggy issues and the rainbows go away, and I can enjoy what looks like a pretty damn good image for under $1K.