Wow! That's taken quite a beating! Are you resting a .270 against it at the range? Ha ha.
My 1.75", purchased around 2002 ish, has held up really well, although I'm apparently not as active as you. A few dents a a few chips, and it's not truly flat anymore, but it has held up great. The back isn't discolored at all, although it's textured rather than smooth like the 1".
I would like to mention that I take it off before going in the ocean. The sea has reclaimed many of my things.