Putnam brushes are great especially on Epic based cans like the Monster stock and P2k2. Never managed to get them to work on TOP cans like the Hellfire/Core stock motors.
They seem to lose some power when the serrations are worn out. Best to reserrate them when the serrations are gone.
They do wear the comm out more but that is the price you pay for performance.
My personal favourite all-round brush is the Reedy 767. A little less power and comm wear but performs consistently over an entire race day (~5-6 heats). Probably something to do with it retaining serrations for much longer.