Subwoofers

I believe Vandersteen 2w and 2wq's are often paired with Maggies to great results.
But, I am prejudiced, cause I own them.
I have also heard good things about Hsu subs in terms of sound, but not regarding pairing with Maggies.
Have you checked the Agon post archives?

I am looking at theSVS subs does aanybody have experience with them? 

The Rythmik subs are gaining a reputation as working well with Maggies. A couple of guys with MG-IIIA's have expressed their satisfaction with the F12 and F15 models on the company's forum at AVS. I use the Rythmik/GR Research OB/Dipole Sub with my Eminent Technology LFT-8b's and Quads, but they're not for everyone. Read about that sub on the GR Research website---it's very special, and especially good with planar speakers.

I'm also thinking of trying magnepan DWM bass panel.