I have the FastCap hot knife and do use it occasionally for Kaizen foam projects. I actually bought a Styrofoam hot knife that has a long rod for a heat element to cut my Kaizen foam, as my company does not allow for the use of the type of blades on the Kaizen foam knife due to safety concerns. For you Hot Knife, an idea for improvement would be a heat shield around the shaft of the knife to prevent accidental contact with the sides of the foam cutout you are working with: I've accidentally hit the sides of a deep pocket with the shaft, and messed up an otherwise good looking organizer. Not sure what kind of material you could use, but insulating or shielding the shaft would make this knife even better.
It's a good point. We will look into it and see if there we can come up with some solution.