Neither is the latest 1.U6 firmware, or any modded version for that matter, official. Using any of them voids a warranty. So not sure what point you are trying to make ???
Why not just leave people to make their own judged choices !
And for your info, I also choose to use earlier versions of 3520a firmware because they gave a quality I am currently happy with.
Just for interest, I have tried virtually all modded versions as they became available and found no real benefit to my situation.
The only firmware mods I choose to have where available are Auto-bitset, Riplock and RPC1. And to that end, I am currently trying the appropriately modded 1F3.