Just to be clear - to me, the sims just mean that those positions are worth trying. This thread is all about the quarter width/height position and demonstrate how good it can be but the sims show that the corner is as good if not better and corner has advantages for the mains. Corners are known good positions for woofers as well as full range speakesers. I plan to use a couple of helper subs along the sidewalls near the back in conjunction with corner full range 3-ways, with woofers at the heights illustrated in the sims.
No matter what I do, I always end up with some sharp nulls around 150Hz. These seem to be ceiling bounce related and I'm hoping these will be taken care of by overlap between mids and woofers. The simple REW room sim doesn't allow that to be modeled.
Marty: If you see a peak, you can be fairly confident in being able to knock it down with EQ. Nulls/valleys need to be filled in by helper subs or choosing another position for a helper sub or the listening position. I think its lots easier to move icons around on a screen than 75 lb+ subs. Still these are just simulations and reality will be different. The simulations assume the drivers on the front wall are embedded in absorber, which takes care of boundary reflection nulls and no doubt affects baffle step. You may need to bring some of that absorber, not the full thickness but 2-4" around the corner and up the side wall a few feet.