Respectfully disagree. (Not about PJB gear being well built -- it certainly is.) My C8 cab has never left me wanting for low end or volume. Now granted, I play a 4 string bass, and perhaps my opinion might be different if I played a 5-string or more. But my C8 cranks out a low E as well as anything I've ever played through, and I grew up on 15s.
I have to agree. A C8 should smoke any traditional style cab with 10s, easily.
I have a friend that plays Dingwalls w/ 37" B strings through PJB cabinets.. the 100 pound plus monster cabs that have like 12 or 16 (or more) 5" drivers in them. Those cabs produce the deepest, loudest, and clearest low notes possible. He could crank the power to those cabinets and literally hurt people, and never lose definition. I know because I have felt the beating to my rib cage! If I wasn't into a more tube amp and vintage driver sound, I would say PJB makes the best cabs in the biz, hands down. But, they're not my thing.
I never played the C8, but I tried their 2 and 4 speaker cab offerings when I was looking for something small and light. In direct comparison, the barefaced one10 vs. the C4 was an easy thing: The barefaced was much lighter (IIRC the C4 was just over 11kg, the barefaced at 7kg), and while both sounded great at lower volumes, none of them shying away from a low B, the C4 could not keep up with the barefaced once you turned up a bit.
For my personal application neither cab was enough to gig with, but what I took from this experiment was that while the C4 is on par with a decent 110 cabinet, it looses against a stellar one - so I could imagine that a barefaced two10 beats a C8.
And a barefaced 1x12 cab beats a barefaced 2x10.
The PJB stuff gets you a stellar experience if you're into HiFi modern bass sounds.
The idea of doing that with lots and lots of too small drivers shows a very determined, intelligent mind that is also slightly mad behind the R&D process.