These foams/gels work good on paper, however you to have to keep in mind that the average homeowner may be applying these types of products. If they miss spots...which they will or do not apply sufficiently, all it takes is one spark in a crucial missed spot for a fire to take off.

Also those houses, especially with vinyl siding will still be vulnerable from the intense heat as once the siding melts to the ground into a puddle, this will expose the house structure to the flames.