VU 55" 4K TV is a hdmi1.4 model supporting upto 4k25p only.
My setup: TataSky 4K STB connected to the HDMI(UHD) port of VU 55" 4KUHD TV with the HDMI cable that came with the STB.
Given below are my observations.
Case 1: When STB output is set at 1080p @ 50Hz.
1a:The SD channels look more worse over the earlier 1080i STB.(upscaling from 576i)
1b:The HD channels look slight improvement over the earlier 1080i STB.(upscaling from 1080i)
1c:The 4K channel looks better than the StarHD1.(Down scaling to 1080p)
Case 2: When STB output is set at 4Kp @ 25Hz.
2a:The SD channels look more more worse over the earlier 1080i STB.(upscaling from 576i)
2b:The HD channels look more worse over the earlier 1080i STB.(upscaling from 1080i). Lot of judder
2c:The 4K channel looks more worse than the StarHD1.(downscaling to 4K25Hz. I presume TS signal is 4K50Hz) Lots and lots of judder.
Case 3: When STB output is set at 4Kp @ 50Hz.
All the channels, there is picture but no color.