I have both here, a BA and a SM and both have the same stopping power and can lock the front wheel. If you have enough to lock the wheel you already have more than you can use. Only advantage to the dual disc is it will stay cooler and if running extremely hard it won't fade as soon as the single.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!