Shoreline is a private labeled Dynasty.
At my previous job, we had access to Shoreline/Garden Leisure through one of our distributors and would occasionally bring them in. Probably sold 15-20 over a 2-3 year time. While I don't know how they are holding up today, I estimate that we probably had at least 50% require a service call within the first 2 years. In my opinion, they are a mediocre hot tub made by a mediocre company. The insulation was lacking, the craftsmanship was average, the cabinet and frame were below average, they were not efficient due to the lack of insulation, poor fitting covers and big pumps (they are 5HP, not 7HP, just an FYI) and I have never been a fan of Gecko electronics. This model did not exist when I sold them but they were not the most comfortable tubs, at least to me. Ignore the lights and stereo.
My current employer sold Caldera from 2014 -2018. We probably sold 50-60 of the Vanto's and Marino's. I just looked through our service history, 4 service calls total (pump, cover, control panel, plumbing leak). Caldera (Watkins) is good to deal with from a dealers standpoint. The Vanto is in my opinion a comfortable hot tub, has decent power, is energy efficient and an overall better built product than what you would be getting with the Shoreline.
You should also research your dealers because their after the sale support or lack there of can be almost as important as the hot tub you purchase. Also, pricing. If my memory is correct on wholesale pricing, that Shoreline is probably a fair amount more expensive than the Caldera.
