Europa Owners - What Sub?

I am actually in the process of finishing up a Europa based system right now and posted a similar question recently (although I didn't state that it was for the Europa's, just monitors in general). The consensus seems to be to get the best REL sub that your budget allows.
However, Roy actually has a new sub coming out pretty soon. I would have to assume that it would tough to beat that combination, and I think it is going to be pretty close to this price range.

If I'm not mistaken Roy's new sub will be passive.

Roy has new sub out soon but if you can't wait he recommends getting the Titanic DIY Sub from PartsExpress, then get the damping material from GMA. He said this is a killer combo. Another excellent but different choice altogether would be James EMB-1000 if you can swing three times the dough 8^)