They would also be underpowered and not have optimal air space as well. All a factor. If you ask me, it'll come out in a wash. IMO the two will be slightly louder but the 3 will move more air.
so 2 in 6cft on 2500-3000 watts rms each will be safe?
I'm willing to bet that is exactly what your looking for.
I don't get your response