If you have the space don't go in-wall. You make a lot of sacrifices for decor reasons.
I have an HSU 3.0 setup that I really enjoy. I have never heard the Ascends or Arx, but after reading this thread and seeing that many very well spoken, reasonable, and polite people prefer the Ascends, I am seriously considering sending the HSU's back and trying them.
FWIW, I have talked with HSU a number of times via email and they have been very responsive and helpful.
I don't think any particular speaker recommended in this thread (HSU, Ascend, or ARX) would be a wrong choice. In general, AVS is full of helpful and knowledgable people. You just have to learn for yourself who to listen to.
Enjoy the journey and good luck!
If my budget had been a bit bigger I would have gone Wharfedale 10.2s.