For movies, the dynamic volume will shift depending on how the movie was recorded. I can easily hear whispers and clear dialogue with my vertical bookshelf center setup, but when it shifts to a loud scene, the speakers will still get loud. As it should with all setups. No extra center boosting necessary here, no problems hearing whispers. Some actors may mumble, but that is the actor's fault for you not understanding, not the speakers fault. You can tame the action scene peaks with audyssey dynamic volume if you wish to do so. For night time viewing, I usually turn it on.
For me, it seems like a vertical bookshelf is a no-brainer for clear dialogue. But browsing this forum, it is clear that I'm in a minority.
I see people complaining all the time about dialogue and looking for bandaid solutions such as boosting the center channel level with their avr. Then they try to get bigger and wider centers to fix their problems. They may place their centers in a bad location too and try to fix their problem with a more expensive center. Positioning is a lot, do not neglect that. I could improve my setup as well with a wallmount, but I'm satisfied for now.
Honestly, I don't know why there are not more supporters for vertical bookshelf. It is a cheaper and most likely superior to the dedicated center in the same line.
Is the infinity p163 in the same class as the HSU and Ascend? I have never listened to the HSU and Ascend myself, so I have no opinion on it. Many will straight recommend things without ever hearing them. I do not do that anymore. I only suggest taking an audition of something if I feel it has potential.
However, many have recommended both brands. Also, ascend seems to tout being a neutral speaker, which I tend to lean towards. I myself am beginning to lust after some ascend cbm-170se as I'm looking for some nearfield bookshelf speakers for my desktop and think it might be a good option.
But again, I have not heard the HSU and Ascend. I did listen to the kef q300 I mentioned earlier. Not in-home but for a good while in the audio store, sitting in a perfect triangle from the speakers for a good 30 minutes with the avr in direct mode. I can comfortably say that I would prefer it over my infinity p163.