At 2000 PSI, PoP will actually rub off on your fingers. After a few months of "normal" handling, the edges and corners will look slightly "eroded". The paint is actually stronger than the underlying material, so a good thick coat of paint can actually protect it slightly. Anything that gets dropped on a PoP project is likely to leave a chip showing through the paint, and if one of the pieces itself gets dropped even a few inches, or jostled in transit against another piece, you're looking at a need for repairs or replacement of the broken section.

I use USG Hydrocal (5500-6000 PSI), and it still gets "dinged" on occasion, requiring some touchup paint to hide the chips, but far less than with softer material. I had one finished piece get dropped off the edge of a table onto a carpeted concrete floor by a klutzy gamer ("I didn't think it was going to be so heavy..."), and it shattered into several chunks, fortunately along the glue lines for most of the breaks. A couple of blocks got crushed on the one corner where it hit. Fortunately, I had used Titebond II, which is water RESISTANT, but not water PROOF, so I was able to soak the broken spots with water and eventually removed and replaced the shattered blocks with only moderate difficulty.

Excalibur is far more resistant to the routine chipping that most pieces get subjected to during play, but I discovered that if you accidentally drop one Excalibur piece onto another, one of them is going to shatter like glass. That hardness comes at the expense of brittleness.