I upgraded from a 5030UB to the 5040UB. The 5030UB is great but lacks, of course, 4k enhancement. I have it mounted from the ceiling so the larger size is not an issue for me. It is 17' from my 150"; screen and I sit 15' from the screen. My theater is completely light-controlled with no windows. I have Dish and a PS3 for streaming. Currently, my only 4k source is 4k recordings of the Rio Olympics.In many 1080i programs, I see no difference in the picture quality. Newscasts, however, are better. I don't know why the difference.On most Blu-rays, I see little to no difference. The 5030UB and the 5040UB are both pristine in 1080p. In some, The Pacific, for example, the picture quality is somewhat better on the 5040UB. I don't know why the difference.Turning to my only source for 4k (currently), I was immediately stunned and elated by the picture quality! I have basketball, track and field, and swimming recorded from the Rio Olympics on Dish's 4k channel. The picture is stunningly clear! Bright, clear, and colors pop. I am eagerly awaiting the release of the Panasonic DMP-UB700 and Oppo UDP-203 UHD players. Based on the Olympic recordings, 4k discs should look astounding. I cannot currently test the HDR capability.The 5040UB has other improvements over the 5030UB, including remote-controlled lens control (far superior to the manual controls on the 5030UB) and slightly more light output at 2500 lumens. This is so bright that I can run in ECO mode and it is still plenty bright (though in a completely darkened room).Unfortunately, at 34 hours, the lamp refused to turn on. However, Epson's warranty is fantastic as after just a 10-minute phone call, Epson had a brand new unit in my hands the next day at no cost to me.I will update this review after I test it with a 4k disc. In the meantime, I've included several photos. The Oblivion shots are on Dish 1080i. The Olympics shots are in Dish 4k.UPDATE 12/16: I swapped my PS3 for a new Roku 4k and the Oppo UDP-203. UHD image quality very much depends on the source. At best, the picture quality of my 5040UB, on my 150'; screen, makes it look like a clear window that I can step through, including on Dish 4k or even UHD nature YouTube videos. There is a noticeable improvement in resolution (or perceived resolution) between 1080p and UHD, but the bigger difference is between SDR and HDR. Colors in HDR are much more vibrant, though to offset the darker image in HDR mode I have to change to Cinema Bright mode, and I often choose to switch from HDR2 to HDR1 mode. UHD movies look great but so far it seems most discs are upconverted from a 2k intermediary so the resolution improvement is modest, However, the improvement from SDR to HDR is significant.UPDATE 4/18: At about 1,479 hours, the projector suddenly failed to illuminate. No warnings. No degradation in picture quality or brightness. I got the flashing light code indicating lamp failure. Epson sent me a new lamp free of charge and all was well again. Nevertheless, the lamp's estimated life of 5,000 hours in ECO mode was more than triple the actual life of this lamp (I ran in ECO mode almost exclusively).UPDATE 2/19: After 10 months and about 700 hours on this replacement lamp, the projector again failed to illuminate suddenly. Again, no warning and no degradation in picture quality or brightness. This was the third lamp failure between two brand new units, and now I was out of warranty by more than four months. However, Epson came through again! Even though the error code indicated lamp failure, Epson sent me a refurbished unit with the understanding that I would get no warranty extension. I did not understand why they sent me another unit instead of a new lamp, but I wasn't going to argue. The refurbished unit had no signs of wear and I am sure included a new lamp.I was very aggravated that another lamp had failed very early and I had to go through the time and trouble of taking down the projector, shipping it (no charge), and mounting the replacement. I've decided to downgrade my rating from 5 to 4. Further downgrades seem too harsh as the picture is absolutely gorgeous with high quality sources (streaming 1080p or 4K, or 1080p or 4K discs), and Epson really stood behind their product. I've read reviews of newer projectors, and watched YouTube comparison reviews showing the picture difference between the 5040UB and others, including true 4K units. If I were buying today, I would buy the 5040UB again because of the outstanding picture quality, Epson's support, and the current price of just $1,999.If you are concerned that the 5040UB is faux-4K and not true 4K, don't be. Unless you are sitting within a few feet of the screen, you won't see any difference in detail. Check out the YouTube videos showing side by side comparisons. You will, however, see the exceptional color and contrast of the 5040UB is superior to anything else in it's class or in lower classes.