Combustion helper is really a great mod. And EJ crunched a bunch of numbers which apparently say that it's better to wait on combustion until you get a really big ignite from Pyroblast, even if you don't use combustion each time it's available.
But ya... gear has a lot to do with fire. Frost is still more consistent for me, and for progression, I pick consistency.
You could be fishing for a big pyro crit for half the fight with current gear. :\