The MX is a great sub, quality is outstanding. If I had the money to afford it, I would go with it all day over an Fi/AA sub, just because everyone and their mom has a Fi/AA sub, and the build quality isn't matched from Fi/AA. If budget is in issue, you may want to check these out, but if your in the market for a excellent SQ sub and outstanding build quality, and a sub that doesn't use the typical 12 spoke basket, than the MX is definatley a good choice for you.

I have heard great things about the AQ1200s, but never have owned one or seen one in action. I would probally use a single 2400 in the rear and a 1400 or 2000 as a starting battery, with the big 3 of course, that should be more than enough.