Choice of shapes, ease of installation, longevity, incredibly-reduced maintenance, never a liner replacement, and finally, never a scuffed knee or nose from a gunite surface. Almost infinite color schemes, too.
The long-time pool installers in the area had nothing good to say about Fiberglass Pools…until a few beers on the patio induced a salesman to offer up that pool companies thrive on Service and Repairs; not sales. Open a yellow pages or go online and see how many companies are Gunite and Vinyl Liner repair experts vs how many of them sell new pools. Once you pay for a fiberglass pool your not hit with expensive repairs over time.
I liked San Juan pools because their locations told me that they weren’t local or a lightly-funded operation. Seems they’ve added locations since then, and they DO have a dealer in the North East.
Frost line damage would be more severe on a hard object than on one that has some flex in it. However, you’re going to have the pool dropped into a hole in your yard by a crane, then surrounding fill will most likely be sand, so freezing won’t be an issue from the outside in. Check them out.