With CEDIA going on right now, a lot of new products are being announced. The Mitsubishi HC7900DW, for example, was just announced.
I would be looking for current products with announced replacements to start to come down in price. Maybe start looking for the Mitsubishi HC7800D to come down into your price range now that the HC7900DW is in the pipeline.
Also, I've seen decent deals on refurbished JVC D-ILA units. Check the Found Deals forum for more info. Those would fit your profile for modest light output and would address the RBE problem. I am also sensitive to RBE and, while I appreciate the other attributes of DLP, I'm not sure that my next projector won't be LCD or D-ILA.
EDIT: Forgot to mention, I would definitely not get the HD20. It's getting pretty long in the tooth at this point and the HC4000 has more going for it with DarkChip 3, more zoom flexibility, etc.