I Used to be an owner of an 885es/ 760es and had issues with 3 of them. Sony was good too exchange them and I only had to add $4K to get a 995es / 870es Unfortunately that had problems as well. Optical block issue. The whole guts of the system. I would have to say Sony had great service and the projectors did throw a great picture unfortunately I just ended up with 4 duds. I ended up with a full refund but still its a damn shame. Apparently the 270es 570es 760es & the 870es have all the same internals bar 760es and 870es. Their difference was Laser and 870es having the lens. With the 760es and 870es with the amount they charge they should of had a much higher end optical block, processor etc. Just under the 5000es.
Your experience reminds me of mine with the Epson LS10000. I went through several replacements; all had poor grey uniformity which could not be calibrated out and was very noticeable in content. I ended up getting a refund from them. I will say, their customer service was phenomenal.