Hey David,
Thanks, this is interesting, please continue with the posts. I'm curious to hear what you think when you explore other positioning formulas and to know where you finely settle. I tend to think the room is so unique that the right formula for your room may not be the right one for another room. But it makes for fun experimentation although it's time consuming.
BTW, attached is another method you might want to try called MasterSet that Sumiko released maybe a decade ago.
For another long and technical read on the subject you might pickup Toole's book Sound Reproduction - Loudspeakers and Rooms.
Robbie