Well, he is comparing it to the older fathom F112 and not the newer F113 which is much more highly regarded and which the PB13 Ultra is rated even more highly than for half the price of the F113. But none the less it does sound like a promising sub only problem would finding a dealer or shipping costs.
The sub I have been looking at lately is the MFW-15 over at av123, now that seems to be the best bang for the buck, still under $1000 delivered to my door but have to wait till July to see/hear one if I ordered now.
The PB13-Ultra is a fine subwoofer, SVS finally made a great sub with that design. The notorious mid-bass FR hump, found in most of their old products, was finally flattened which made it much more articulate than the low end thumpers in its line. (Extension in the SVS lineup usually came at the price of nonlinear FR).
Last year we compared the PB13 Ultra to a Paradigm Servo, Fathom JL113, Velodyne DD-18 and the EP600. The comments were mixed as to which one was the best sub, but everyone put the Servo in last place which tells you alot about the quality of the other subs.
Sealed and ported subs have different strengths. Ported subs will always deliver more output down low but at the cost of some port noise. Sealed sub will have less output but come across as "tighter", "faster" and more detailed. With these subs the line gets blurred but IMO its still safe to say that for strictly HT applications ported subs give you better performance because of the extra output down low while sealed subs are more "musical".
With regards to the Fl113 and PB13 Ultra, if HT was the main application I would lean toward the Ultra. But with music no contest in favour of the Fathom. That result was clear from our listening test. Lists that say otherwise are misleading and unscientific BS.
As for the EP600, it holds its own against all these subs even though its an older design now. Its great for HT and much more articulate than other ported designs. One of the guys in our shootout last year ranked it tops in the blind listening.