Auto Accept is great to avoid unwanted ARCOS notifications for trips you won't get. It can gum up the system if everybody uses it, because everybody using it gets their 12 minutes to accept/decline before moving to the next pilot, but that's a system issue not a pilot issue. It means if your phone rings, the trip is yours if you want it.

I've never used auto Ack since it effectively removes the proffer aspect of an award. I'm not sure how it benefits you unless you will literally take ANY proffer you can get your hands on and don't want to be worry about getting to the phone in time (or you're in the middle of a flight.)