We just got through talking about this same thing this morning with one of my new ff's assigned to my engine. I told him that I did not want him wearing his facepiece until we were ready to make entry. My reasoning is for some of the same reasons already listed; take a min. to get a good clear picture of the building without the fogging or scratches in the mask. It's easier to see, feel and hear hazards without the facepiece and nomex hood. Once these are in place we have completed our encapsulation. Another similar item we talked about was taking the hydrant without an SCBA at all. When laying in, I see ff's dropped off at the plug in full PPE including SCBA (sometimes even wearing a facepiece). Why does a ff need to be wearing a pack when laying a line. Reduce the weight, visibility problems and entanglement hazard and let them pack out when they get back up to the rig.