The π cornerhorn is my favorite configuration, and I try to use them wherever I can. I think corner placement of woofers is ideal, and that the dispersion characteristics of radial vocal and high-frequency horns allow them to be placed in corners as well. You don't get floor bounce from a horn that has very limited vertical dispersion, and if its horizontal flare is 90o then it matches the horizontal pattern of the cornerhorn's woofer.
So I like using room corners and I always try to take advantage of them. If a room has two good corners, I'm going to put π cornerhorns in them. I can't think of a single time when they weren't the best implementation available to me in homes having listening rooms with appropriate corners.There are problem rooms, like those with raised hardwood floors or those with closet spaces or halls that develop annoying resonances. But those conditions color sound enough that you can even hear it when you're just talking. They have that "singing in the shower" quality, a resonant chamber that is obviously boomy in the midbass and lower vocal range. These will cause problems for any sound system installation, and aren't limited to cornerhorns.
If I have two good corners to work with, I'm going to use π cornerhorns. They're great for most rooms of 500 to 2000 square feet, as long the corners are right.