bgilly, you are making the same mistake I have made. You are making quantitative comparisons because you can. Total SPL, amount of displacement, number of drivers, dollars per max db. These are easy to make comparisons. What people have been trying to pound into my head is that you, and only you, can make the qualitative comparisons. Does it sound better to you. If yes, is it worth spending the extra money to obtain it?
You have to realize, some people like boomy subs and would be very happy with an inexpensive sub. Some people have more refined taste, but not much cash and have to settle for budget subs. Some people, like me, are satisfied with a mid level sub even if they can discern a difference in the higher priced subs. Some people will spend the additional amount for the perceived improvement in sound reproduction, even if the improvement is slight and the added cost is great.
And don't fall for the vocabulary challenged posters that can only use terms like, 'X will blow away Y', or 'X will stomp all over Y'. They are just trying to goad you into an argument.