There was a thread on here about the POR15.
If my memory is correct, it was not a positive thread.
I would suggest you try to do a search for the thread.
I'm not familiar with POR15 but it doesn't have much background information available. I just went through the process of deciding what to put on my floor and I would recommend going with epoxy but expanding your possible vendors. You should talk to Justin with GarageFlooringLLC, Scotty with Legacy Industrial and Fred with Alpha Garage as well as the Epoxy-Coat people. All of them can give you good information and great customer support after the sale. You can then make an informed decision an which product to go with.