Updating Or Rolling Back Your Mate 7 TL-10 Does It Affect Device Or Damaage Device

[AC Question]

Good day I have a mate 7 tl-10 gold iv update it from kitkat to lollipop and update it again to marshmallow. Marshmallow was not working so good because notifications didnt come through and when opening an app i have to click it twice than it open so i rollback to 5.1.1 3.1emui. A friend of mine told me its not a wise thing to do to update or rollback your phone because there a 50/50 chance that the phone wont function correctly. Whats your take on it? Which marshmallow version is for south africa?