Have flown the 757, 767 and 737 w/o autopilot but with A/T on. You do have to understand the pitch changes with thrust. Would advise not using it when you were new on the airplane.
It was pilot preference as to which way you do it at my current operator on the Boeings. Airbus A/T required and can't dispatch without it.
They were recommending leaving it Armed if you disconnected it. This was mentioned in a previous post. As well as speed protection, it also will give you autothrottles in the go around as well.