In both case this is the SKHCXM rom, wich correspond to the Alioth China ROM. They are exactly the same and work with Alioth device (Poco F3/Redmi K40)
I didn't seen any disadvantages compared to MIUI v12.6
The battery is as good as it used to be on 12.6
I still stand 3 days with my Poco F3 (low usage, i'm not a big phone user)
Go for it if your phone support it