I think the only reason I would go brushless, is the longevity of the motor compared to brushed.
Brushless is, as Selatio says, more efficient.
I think its like a comparison between a 2L tuner and say, a 455 BB.
You can get the same horsepower out of both, but the 4 banger will never get the same torque as the V8.
But people go for the 4 because it requires no carb or timing tuning etc... and it's cheaper on fuel, and it will go 300000km before it needs a rebuild.