...I'd like to know what you have to say as I'm somewhat considering building one of these rooms.
I'd say you have a lot of reading and math to do before building a non-standard room. Floyd Toole has done the math but it's still not plug-and-play.
Loudspeakers and Rooms - Working Togetherby Floyd E. Toole, Ph.D.
"Some have argued that there are advantages to using non-rectangular rooms. The thinking behind
this is that, by reflecting sounds in directions other that directly back towards a parallel surface, the
development of standing waves will be inhibited, and diffusion will be increased. The reality is that sloping
the room boundaries has a substantial effect on the modal structure, but the modes do not disappear. In fact,
the magnitudes of the variations in sound pressure throughout the room remain much the same, but the
frequencies of the various modes are changed in an unsystematic manner, and the nodal lines are
repositioned in a manner that is not always obvious [3,4]. Simple predictions of the kind just discussed are
no longer possible, and one must resort to finite-element analysis or models in order to predict what might
happen in practice. This is a serious disadvantage in some situations, as will be seen, for example, in
Section 2.2..."
The article above plus more room and loudspeaker articles by Floyd E. Toole, Ph.D. are available for free in the Acoustics Circle
https://www.audiocircle.com/index.php?topic=58304.0