Well the A10X in the Apple 4K TV has around 2.5x single core performance and above 2x Multi Core performance compared to the Tegra X1 in the Shield TV (going by geekbench scores).
The Tegra X1 will be 3 years old soon. I mean it was a beast of a soc in the last 2.5 years, but its not the top dog any more compared to ATV 4K.
Only reason I got the Shield TV was the native 4K support for some Aps like Netflix, Youtube, Amazon etc.
Its not a great device for Kodi use, there are too many bugs, issues and limitations. It clearly wasnt meant to be a Video device but rather a Streaming console/casual android console. Its Video capabilities that are built into the SoC are very basic and nothing for Video enthusiasts. In particular the upscaling quality sucks and the deinterlacing quality is average at best.
The moment I buy a new 4K HDR TV, probably a higher end Sony, that has all these Apps onboard, I will have no need/use for the Shield any more.
Right now the best combo to cover almost all scenarios and needs would probably be ATV 4K and a Kaby Lake NUC.
To get back on topic though- Im using the Minix U9H with LE build from this thread on one of the older 1080p TVs. I thought it can convert HDR to SDR correctly, according to your thread in Kodi forum wrxtasy .
When I play a 4K Hevc HDR file on the U9-H connected to the 1080p TV, the colors appear to be correct (not washed out), however the image is too dark. The gamma level/contrast level is wrong. It results in black crush, the image is darkened too much.
Now I read in a change log from Minix that they fixed this issue with a Firmware update a while ago. I have the latest FW on the U9-H and still have this problem when using on an old 1080p tv.
I wonder if its a LE bug or a Bug in Minix FW still..
I don't know where you are getting your facts from? Koying is the developer of SPMC and the main release is still Jarvis so that would probably explain half your problems if that is what your using... as for him being the only developer working on the Shield that could not be more further from the truth.
I own both the Shield and the U9-H and even though it is 3 years old it still beats any other ARM SoC device hands down and I would choose it over the U9-H any day of the week, it can't be that bad as well otherwise Nintendo would not have chosen to put the very same SoC inside of the Switch, to say it is full of bugs and problems is absolutely ridiculous it's had more updates than most Android devices that are on the market. As for comparing to an Apple device, lol... good luck with getting Kodi on that.
The issue with HDR on AML has been covered so many times, it's not a 'LE bug' nor is it a 'bug' of any kind, it's is purely down to the way the Amlogic SoC handles HDR, it's not something that will be resolved.