Well if it helps, I tune down to A and use varying levels of gain from a bit of grit to raging distortion, and my Four10 delivers the low end in spades. The voicing of the cab works great with distortion, and I always cut through live. The bands I play in are thrash/death/grind so I have to cut through some pretty heavy and loud guitar tones.
However much low end you throw at it, the cab can deliver it. I use a D800+, and even with the deep switch engaged, voicing maxed and bass maxed, the cab doesn't fart out. I don't run it like that personally as it is just too much low end, but the cab can definitely take it.
That helps a lot. I'm sold.