There is no fairfight in BF3. The Battlefield 3 hack is undetected, esp/autospot/aimbot/weapon swap/autoheal are all safe to use. (for myself, I try keeping KD below 5 when I want to play for a long time on an account)
When you start going crazy with damage mod/other weapon kills/raging 500 kills in a round/getting reported all the time, that is when you will end up getting banned.
( If you are paranoid keep BF4/BF3/BFHL on seperate accounts...there is a small chance you might get cross banned, but you have to be a very good cheater to accomplish that )