I don't see much difference in terms of sharpness or brightness when output is at 1080p vs 4K. But I did feel there was some difference between the HD+ box 1080i output and the current box's output in 1080p/4K. The old box I felt was better for normal HD channels but i think the tv needed a bit of tuning for sharpness/contrast etc. to make the picture better. Now i dont notice it to be in any way less in quality than the HD+ box after I changed picture settings on the TV to suit the new UHD box.
I had missed out on the afghanistan vs india warm-up in 4K. I wasn't aware it was being broadcast in 4K or else I would have tuned in. I am very interested to know if the stutter was present in the live broadcast. If it was, this box is going to be extremely useless am afraid. Maybe a software update will fix it but I am hoping its just the discovery communication video content encoding problem.