Advice concerning KStar-10 heater on soft sided pool

We have just recently purchased a HydroForce (Bestway) Steel Pro 12x22x52" (Intex style ultra frame) pool.

This an 'upgrade' from our 15' x 39". Our investment in this pool goes well beyond the initial purchase price so it is extremely important that with our short season (normally 3 months at most), we want to extend it's use as much as possible by adding an electric heat source. Solar options we have used in the past have failed to raise our previous pool's temperature beyond 77 degrees.

Our local pool supplier suggested that since we were upgrading to a 1/2hp sand filter/pump that a KStar-10 would be a suitable choice for us. After a little research I discovered that the manufacturer warns against its use on soft sided pools. I approached this subject and relayed my concerns to the dealer, and was assured (by him as well as a moderator from another known pool forum) that the only reason they are not meant for soft sided pools is due to the notoriously small pumps they are usually coupled with, and with the upgraded pump we should have no issues whatsoever. I made the decision to go ahead to purchase the heater and now after reading a couple of posts on this forum, I have concerns about the safety aspects of this type of heater for our pool. Has anyone has success with this specific heat source on their Intex (soft sided) pool? Or failures? Any info you would be willing to provide would be most appreciated.

TIA for all of your help :)