AzN_plyR, Let me tell you, I did some SERIOUS work to get all that for that price. I visited five different Best Buys (NUMERSOUS times) in 3 states (Delaware, New Jersey and Pennsylvania - luckily, due to me living in Delaware, the farthest trip was only about 25 miles). My trips involved MANY price adjustments and even involved a $150 gift card refund from Corporate for some shenanigans that my closest Best Buy was trying to get away with. All in all, it was definitely worth it (even though my wife wasn't too happy about the whole thing) and I definitely can't wait to get everything set up and start listening. I also have an old Hafler DH-200 amp that I may use to drive the F1's up front. I'll have to do some listening with and without it before I decide.
Yes, if I go with the D-12 or the S12, I would have to sell the dual subs (since I bought them last summer and it's too late to return them). Hopefully, I could get maybe $350 for the dual subs considering that they have extended warranties on them and that they are 400's instead of 4000's (I read the same thing you stated concerning the differences between the two). Selling them would be a hassle though which is why I started this whole thread.
Given what I paid, and what they are, would there be enough of a difference to justify the additional cost and the hassle of selling the dual subs? Sounds like your answer is no.
Sheep, thanks for the insight, especially the comment concerning output. That's something I was definitely wondering about. It also sounds like you may be saying that the D12 might be cleaner/tighter in the low end but with less output than dual 400s?
Thank you (both of you) for taking the time to comment. I appreciate it.