I like the SQ of both of these subs, I can get the W6v2 from a friend for about the same price as I can an Aluminum, but SPL wise, which one is louder for a given power? Assuming sealed boxes, maybe eventually ported. I have a 400W RMS Kicker 400.1 to power the subs, so I'm set with that amount of power.
I mean an Eclipse Aluminum, by the way, for any of you who didn't catch that. Not sure if there are any other subs that go by the name Aluminum, but just in case.
the W6v2 might be marginally louder, but unless you're going strictly for an SPL system, I wouldn't worry about the differences. just go with the one that sounds the best to you.. I've always wanted better SQ over an extra half a decibel of SPL anyway.