3 Cap 4000ULFs vs 3 FV25HPs:
@ 10 Hz, 3 Cap 4000ULFs are equivalent to almost 12 FV25HPs.
12Hz ~ 50HZ, 3 Cap 4000ULFs are equivalent to 6 FV25HPs.
> 63Hz, 3 Cap 4000ULFs are equivalent to 4.5 FV25HPs.
The LP version allows you to place them along the wall, without taking up valuable floor space. This means you can have at least 3 of them along the back wall and still have a second row of seating. You can also place 2 of them along the front side walls and 1 at the rear center. You can also place the LP version right behind your seats to get the ultimate TR.
Before I ordered JTR Neosis 212HTs, I was strongly considering getting another 4000ULF. Since this one will be at the rear of my HT, I was also looking at the LP version.
By the way, just in case you are not aware, for a $500 fee, Jeff can customize the shape of the 4000ULF. For example, in order to maintain the same performance, he can make the regular 4000ULF 72" tall x 22.5" deep, 65" tall x 25" deep, 60" tall x 27" deep, or 55" tall x 29.5" deep.