A pyroblast Procc gives Instant Pyroblast with 25% more damage where a PoM Pyroblast dont. When you get better gear its not uncommon you get 3-4 insta pyroblast when using AT. And ignite bank are just 4 sec. So just from that it can be a dps loss and if you then count in scorch is much you better for moving PoM doesnt look that great. But tbh in the end its about luck.