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
Why are there more and more useless questions every day. Guys, please read and look for an answer BEFORE you create a post, most of the time your questions have ALREADY been answered