I have the 2 piece fronts and have had them for 2 years or so now. They are very stout. Without the outers, my tires threw a ton of road/trail much on the jeep (more of an issue on the road really). I rarely take the outers off of them now. I do not have the MC rears. I smack the rear fenders enough to not want to have to refinish them all the time. Just pick up the plastic one and throw it back on or in the back of the jeep.
My wife has the newer one piece on her jeep (both front and rear). If I were doing it again I would probably go with the one piece both front and rear.
I have jeeps. I do shit to them.