You could also try lowering the XO, but off hand I don’t know the extension capabilities of the Def techs. That could alleviate some localization, but I couldn’t guarantee that as a whole it would improve. Also, if you’re really in love with sealed, the sb2k is a much better subwoofer than the 1000 is, but I’m still a believer in ported subwoofers overall.
As for the Klipsch, I wouldn’t use that at all. Especially to gage how an SVS ported sub will act. They’re just too different. You might find some valuable information by trying it out, but just stay clear about the fact that the Klipsch will sound boomy and not as articulate as the pb1000, and especially the pc2k.
Also, IMO the downfiring PC’s don’t really affect localization at all.