Dave,
Frankly, you're not going to get an objective answer in response to your question. Essentially, you're asking the age-old question, SVS vs. HSU, for which there is no right or wrong answer. The HSU owners will veer you towards HSU, and the SVS owners will veer you towards SVS.
I was in the same position you were a few weeks ago, and I was looking for the consensus one way or the other, and there just is none. SVS and HSU both have wonderful reputations, and having purchased the SVS PB1-ISD a few weeks ago, I now see the benefits of having a "real" sub like an SVS or HSU.
Out of your choices the PCi and PB1 should sound very similar per the guys at SVS, especially if you tune the 25-31 to 22hz as many people do. The PB1 is tuned to 22Hz as well. I have never heard the HSU so I can't compare it. Standing alone, the PB1 has added so much to my music and movie enjoyment that it is hard to describe. Good luck.
