Toe-in or NOT toe-in ??

When you hit the right angle of toe-in, you'll know it. Imaging will still be very specific, but the tweeter won't beam at you. I have had 2 pair of Spendors,(SP100 and 9/1) and their manual tells you to face the speakers directly at the listening position so that you don't see the sides of the speakers, but in practice, that was never the way that sounded most natural. Trust your ears.

It all depends on the speaker.
Opus, equilateral triangle setup and rule of thirds are not the same. Rule of thirds is dividing the room in thirds starting off the back wall.

Chasis...You are correct. I mis-stated, confusing rule of thirds with a different term I had seen someone use to describe the equilateral triangle configuration.

My apologies too for mis-spelling your name. It's been one of those days!

Trust your ears! Try it both ways (having a helper shift the speakers while you listen with eyes closed). Really depends, IMHO, on the speaker and the room. My Spendor 1/2s in nearfield are pointed right at me. Downstairs, my SP100s sound best straight ahead and sound "off" with any toe-in whatsoever!