I have GoPetPlan for my two dogs, both mixed breeds (makes a HUGE difference in price compared to purebred). I've never had to use it, but would rather have it and not use it than not have it and need it. Years ago, hubby was laid off, I had to make "the decision" because I could not afford emergency exploratory surgery. Won't happen again, as long as I can afford the monthly payments for insurance.
I had VPI (Veterinary Pet Insurance) before GoPetPlan, but they did not cover hereditary problems (I had a full GSD at the time). They also had a YEARLY limit on what they would pay out. As far as I know, GoPetPlan has no yearly limit (they have a lifetime limit) and they do cover hereditary problems (NOT pre-existing). I have NOT had to use GoPetPlan (fingers crossed) but I DID use VPI and the insurance DID run out before the year was up---I was not happy. That's why I switched.
I might add that I am not very disciplined at saving money for something specific---I would end up dipping into the money set aside for vet bills on something else.