Let me just add, there is really only a tiny bit of relative "SQ" coming from subs. The bottom frequencies are pretty hard to mess up too badly. If you are using the sub for how its meant to be used (crossed over low, not playing midbass) you probably wont hear an SQ difference in either sub, or any sub that goes for over $100. SPL is different though, but since these two apparantly match up well, get you favorite brand or the cheapest one.
I'm just sick of hearing so much in depth talk about sub SQ. SQ is a subject for the higher frequencies where it is actually noticable IMO, not 70hz and down.