Reaver question

I am using a build with SRS, 2 storm mages, 11 reavers and 2 clerics.

Should I use Brutality gem on reavers or should I use a gem that supports fire damage somehow instead? With the flamewall and hound igniting.

Heft, martial tempo, heavy swing and brutality is my current setup.

Brutality is a dps upgrade for reavers. It does limit their damage type, but is still worth slotting.