Mark,
Though I cannot answer your question specifically, I did own a VK-P5 and later a VK-P10SE w/ Super-Pak phono preamps. BAT's phono preamp was based on the 6922 tube. I also have a lot of experience with BAT preamps. I've owned the 31SE. 50SE and 51SE.
IMHO, you will notice a very impressive increase in performance, particularly in the music's weight, rhythm, and soundstage. That's the plus side. The negative is that these caps seem not to last as long as one would like, and they are expensive to replace. Figure $600 just to replace the six-packs. The Super-Paks are much larger caps, so I believe the price would be even more substantial to replace. The six-packs that failed in my 51SE were only 4 years old. BAT says that they should last 5-7 years.
So they definitely improve the sound, but they are high maintenance. Again, this was just my personal opinion. I hope this helps.
Regards,
John