I have googled for Shotcrete vs. Gunite. I have found information pro on Shotcrete from places that use Shotcrete.

They talk about the quality of the gunite, as far as PSI on the pool walls is done by the person applying the gunite and how they are mixing and applying. While with Shotcrete the PSI is guaranteed by the mix at the concrete facility which is done by computer.

I am just trying to see if the extra money is really needed for ShotCrete.