Additional follow up...

The phoenix unit works quite nicely. Does exactly what I wanted it to do. Turns the room into daylight essentially. I can point the thing straight up and the light from it is, if not natural, at least not nearly as unnatural as a direct facing flash.

The build quality is very cheap, and its system of brackets and screw attachments is downright chintzy and fiddly, but it does *work* and takes care of exactly what I needed it to.