Current PSW111x2 vs. ?

Currently running two PSW111s that were free (promos) to me when I purchased other Pok products. Nice price, free, but I can't help wondering if these two 8" subs are performing as well as one DSW Pro 500, which is the "system suggested" sub for my RTi setup, would.

The Pro 500 is nice-priced on the Ebay store at $279 and I'm tempted to find out.

Was hoping some here had experience with both subs or other recommendations.

Thanks,

Dave

Edit: Would like to include the Micro Pro 2000 in this discussion.
Marantz AV7005
Marantz MM7055
Onkyo DX-755 CdP
Oppo BDP-93
Technics SL-1301/Shure M97xE
Polk RTi A7s
Polk CSi A6
Polk FXi A6s
Velodyne VDR10-BV
Panamax M5100-PM
Antec VERIS A/V Cooler x 2