There are a couple of spots in my pool where the Polaris has worn the plaster through to the dark-gray gunite underneath. I'll take a picture and post it when I get a chance. The worst spot is about 8-10" in diameter in the shallow end at the base of a wall. I asked at Leslie's about this and they told me this product would work to fix it:
A+B Epoxy Putty
A PB told me it wouldn't work and that I should get it fixed ASAP as the gunite is not watertight. He says the rebar in the gunite is probably getting exposed to the water, which is now salt, and is likely corroding inside the wall.
We were thinking of resurfacing the pool this fall, but finances may dictate that we wait until next year. What do you think?