I don't know.
I do know that without measuring software, one will never know what's what with what. I have measured, measured and measured our living room space, over and over and over and over.....ad nauseam......hurled and measured the room some more. Because of this effort, currently, sight unseen, I have a few clues where the best positions are in our living room that will bring out the best in any subwoofers we purchase. Yes, I have a bit more placement and measuring to do, before hitting the "buy-buy-buy" button.
The point, I have no knowledge or understanding of the ULF score, other than it's a sort of genius neutral comparative score that allows for simple, across the board comparing; your room, to our room, to any room five blocks down the road. Obviously, placement and the output interaction with room acoustics is going be a consideration but everybody has the ability to measure the output of any subwoofer placed in their room and with due diligence, for the most part, get the best out of any subwoofer handed to them. The rub, all things being equal, knowing what the comparative starting point (output) of any given subwoofer system is going be? Once known, all that's left, is hitting the hip, making the call and lighting the candle.
From my brief and ever so ultra limited exposure to the ULF score, this number gives one a simple, yet effective score in which to compare disparate subwoofers so one can confidently make a buying decision. As to placement in the room, acoustical measurements and dealing with intrinsic values such as WAF and budget, all are up to the mechanical and diplomatic skills of the person buying and placing the subwoofer into service.
Even though you have to wait another week or so to order your subs it sounds like this marital spat has concluded in a fairy tale ending:
Joe and the dual FV15HPs lived happily ever after!
Congratulations on your future purchase it sound like they will be great.
The location of your sub will dictate the response...more then likely you will still achieve those numbers. Take the time and read the ULF thread...it helped me put things into perspective between going ported or sealed. Its not a end all reference by any means.
4 XS15s @ 0.4 @ 12.5hz = 1.6, 4880/1.6= 3050 - a measly 2.5 stars?! What's that all about?!! Don't sound like 2.5 stars.....
That is only for Ultra low frequency...you likely have a very solid system above 20hz where the bass is audible. Remember that the ULF thread is only comparing infrasonic bass, which is felt not herd. It would take quite a few high excursion sealed subwoofers and gobs of power to produce reference level bass below 20hz in your room.