It's a gunite world. Inc. Master Pools in Tuscumbia, AL, has been building and renovating swimming pools for over thirty years and has used both plaster and fiberglass. He still prefers to replaster when it come time for renovation. Stephenson estimated a good plaster job would last for at least twenty years. Problems of staining, often caused by debris collected in the pool over the winter, can be solved by investing in a pool cover.
Plaster is proven material.
Of course there are shortcomings to plaster, but the shortcomings don't have to do with the product or application but mainly with the care. The cleaning process is with muriatic acid. Many people use too much, and the acid eats the surface off the plaster. Also the pH can be so low in some swimming pools that the water attacks the plaster and eats it up. Stephenson's pet peeve is that more pool managers don't invest in pool covers instead of draining the pool and leaving it to the elements in the off-season.