I also have a Hefty Aluminum up front, for 3 1/2 years now. It's held up really well and I would definitely consider aluminum again. Although I think design plays a big part in it.
As far as rear bumper goes I wouldn't even consider aluminum. Steel all the way. Just too much going on with a rear bumper I think. Beyond dragging and recovery off the rear bumper, think weight: Tire carrier and tire, Jerry cans, Hi Lift, recovery boards, propane tank, Trasheroo etc. Maybe Aluminum if it's the bumper only.
As far as the bumper cowl rubbing and eating through the aluminum, first that's a severely mis-aligned bumper. It shouldn't even be close enough for anything to touch it including during flex off road. That being said mine was also like that for a while and only wore off the powder coat. Not sure how plastic could wear into aluminum unless it was a very long time.