It can be challenging to use a torch without getting off-flavors from unburned hydrocarbons. One of the advantages of the Searzall (which I don't have) is that metal diffuser creates distance, and creates a red-hot screen for the gas to travel through. This eliminates the taint. There's endless discussion on which kinds of gas taste good or bad; Nathan Myhrvold has shown that they're all the same: they taste bad if you don't manage complete combustion.
At the very least, you have to hold the torch at a distance. If any flame hits the food, it better be blue.
Another problem with torches (ironically) is that they burn so cleanly. That ghost-like blue flame is indeed over 2000°F, but there is very little radiant heat. 1000° dull orange briquets or broiler coils (or searzall screens) produce much more infra-red energy, which is more efficient and controllable at searing food. With a gas flame, you have heat that's much too intense right at the tip of the flame (it just tends to incinerate the surface) but as you pull that flame away from the food, the proximity temperature plummets; there's just too little radiation going on. This is why torches are tricky to control.
I use a torch for some things; typically for touching up an unevenly browned roast. For a steak, I'll take a hot pan or griddle every time. I haven't used a Searzall, but suspect I'd find it more useful than my humble torch. A searzall on a monster torch like this new one would be bigger step in the right direction.
