I'd go a single HDC3, if you plan on doing any upgrades. That way you could just get another HDC3 if you wanted more. I run HDC3's and love them, and I've heard many subs and aloooottt of sundownz, but I just like the way AQ's sound. And dont listen if someone tells you "they dont get low" haha that still makes me laugh. Good luck on decideing subs man hopefully you're happy in the end.
Wow ...we must have some different hearing ....chinaman beating on a wok is not what i like ...