I agree that the RP-8000F response is that of a ported loudspeaker!
I picked it because you expressed concern that this FR could be bass-heavy in a smaller room.
However, it is hard to find a good sealed ID sub that does not offer quite a bit more bass!
However, it's frequency response (which may be too much bass if placed in a small room) is much closer to a sealed sub's response than it is to a ported sub's response (referring to the kind of $500 plus subs generally recommended here).
Be aware that the dB scale for the Klipsch is 5dB and the scales for the HSU is 2dB!
Klipsch RF-8000F:
HSU ULS-15 (sealed):
HSU VTF-2 MK5 (ported):
IME (based on the gallery), in small rooms, the sub will most likely be located against a wall or in a corner, so I am not too sure how realistic of a proposition pulling the sub out into the middle of a small room is in practice!
That is a valid point. However, if he tries both as he has indicated, he can find out which does better in his room and if it is the smaller sealed sub ... and the ported sub
run in sealed mode (either of which is where smart money would be bet), the sealed sub will be easier on the back, wallet, and ability to tuck it in more nooks!
Like I said, my Outlaw convinced me that a ported sub can do the job, but I still can't understand the "no way, no how" attitude towards sealed by most here (William Lemmerhirt being the exception in this case)!
In my large volume LR/HT setup, for the music I listen to, the Outlaws are no better than my Rythmik E15HP's. As close as my ear can tell, they are equal. I like the Outlaws better when I listen to HT.
If someone listens to music with deep synthesized bass, that would tilt the scale to the Outlaw, but for me, it is only HT LFE that recommends the Outlaw!