FWIW, I had both the PB-2000 and PB12-NSD in a 2700 ft^3 room and the difference in the two subs was minimal. I think in a larger room the PB-2000 would allow for some additional output potential, but depending on how you run your sub(s) it may not be worth a $300 additional cost. I would rather opt for going dual PB12's.
Subs>RBH I-12e, I-12. HSU VTF-15H mk2. Monolith THX 12(x2), THX 10(x2). XTZ 1X12. SVS PB-1000(x2). Speakers>JBL Studio 270/235c/230/225c. Sony CS3/CS8/CS5. QA 3020i/3090Ci, 2020i/2000c. Monolith Cinema 5bs. Polk RTiA1/CSiA4. Other Audio>Sony MDR-Z7m2,V6, XB900n,700,XB32,XB31. Sennheiser HD58X,HD4.50,PC37X. HiFiMAN HE4XX. Philips SHP9500. SIVGA SV004. SA HDTwo. HyperX CloudPS4. TB Elite AtlasAero. LG FH6,RK8,RK7,PK5. HK Onyx Studio4(x2).