Here's what my piston looks like after 5K miles. It is still there and you can actuallly see a small chip on the lower right corner where it is missing. It's hard to see because the coating was also silver in color but it is still there.

The bad news is that the carbon buildup appears to be worse and was much harder to get off than last time. Not sure why that is because the coating itself has a slimy feel to it. Anyways, pic below.

 

I've done some coatings on pistons too but
it does not look you your afer 10K. The coatings
are all still there. The problem that I notice
when coating is not the material itself but rather
what is being done prior to coating. Preparation
is of utmost importance. That's where human
error, laziness or attitude comes into play.