Just came across this thread. I have a Hotspot FPH system. It does heat the pool, albeit a bit slower than a solar heater would. I had trouble finding an installer too, but the person who ended up doing it is a sole owner of his own small HVAC company. I'd recommend looking for someone like...
I second this, particularly Acme, Tyler, Toolbarn, Toolup and Toolnut. They all seem to have more or less the same deals, which are meh, so coupons would be great.