sub selection

Could use some input here. I am working on gathering components to put a system in an 03 Explorer I just got. Now I got the Explorer for the specific reason of carrying around the little one on the way so saving space is primary here. I have always been more prone to SQ over SPL, and since this will not be my DD and most times I am in it my baby will be to, I did not want to go overboard with alot of equipment.

I got my hands on an OEM sub box that fits behind the factory panel and holds 1 8" sub. Once it gets here I am going to check its internal volume and construction and either use it to hold 1 8, or use it as a mold to build a FG replica that holds 1 10. There are 3 subs I have been considering they are both 4ohm DVC subs:

1.) Elemental Designs 9kv.2 as seen here: http://www.edesignaudio.com/edv2/product_info.php?cPath=21&products_id=29

2.) RE Audio, RE Series 8" DVC as seen here: http://www.reaudio.com/specs.html#sp_re

3.) Image Dynamics ID8 v.3 4ohm DVC seen here: http://www.imagedynamicsusa.com/tech_page.php?name=ID8D4%20V.3&type=sub&id=id

I am going to be using an Eclipse XA5000 to power it so I should be feeding the sub about 400 or so watts.

I know ID have always been the sq sub, the only reason I am considering the others is because I am moving down to an 8" sub, while sq is my main objective I still need something that will handle the lower end well.