Has anyone used a KStar 10 heater to heat a soft sided pool

We just recently 'upgraded' from a 15' by 42" Intex to a 12x24x52" SteelPro (Bestway). We used our last pool for two seasons, using only a solar blanket and relying on Mother Nature to keep it warm. Huge fail. We have been shopping around for pool heating options, and one of the pool stores has suggested we use the KStar 10. Any websites I have visited have warned against using this product on any soft sided pool. When I contacted the pool supply company to discuss it, he assured me that the only reason this was a no-no, was because the flow from manufacturer supplied pumps would not be sufficient enough, subsequently affecting the efficiency and eventually the heater would "burn" out. We are switching out our smaller pump with a higher velocity sand filter/ pump, and he assures me that with the new pump, we shouldn't have any issues. I just cant see the pump being the only reason for the KStar manufacturer warning against it's use on soft sided pools wouldn't they suggest a different pump if this was the issue?). I am very skeptical... I am concerned that there may be other issues with this set up. Does anyone have any more information about this product? Anyone has success or failures they would be willing to share or any other recommendations for (electric) heating? Solar heating is really not an option for us. TIA for all of your help