yes, I see so many 4x10 cabs being used for subwoofers at large concerts. 
a four by 10" cabinet may be louder than a 15" at low mids and upper freqs. It may not. A 15 might go lower it might not. As has been repeated around here a lot, you can not generalize tone just by driver size. I would say that most 4x10 cabs are too shallow to allow all of the drivers to go as low as they may have the ability to.
Generally speaking, having jumped back and forth from 4x10 to 15" cabs my whole life I am pretty sure that 4x10 are louder, 1x15 are deeper. Get more 15" cabs, problem solved.
a four by 10" cabinet may be louder than a 15" at low mids and upper freqs. It may not. A 15 might go lower it might not. As has been repeated around here a lot, you can not generalize tone just by driver size. I would say that most 4x10 cabs are too shallow to allow all of the drivers to go as low as they may have the ability to.
Generally speaking, having jumped back and forth from 4x10 to 15" cabs my whole life I am pretty sure that 4x10 are louder, 1x15 are deeper. Get more 15" cabs, problem solved.
