That's about right. I was once advised to toe in the speakers so a line drawn from each tweeter would intersect about a foot behind my head at the listening position. It worked for me.
Since I have the speakers almost 10 feet apart I tried sitting that same distance to them. You know the triangle thing.
I find that moving back a few feet more brings the soundstage together more.
Ozzy (System | Reviews | Threads | Answers)
The image will change if you sit closer and toe in the speakers a bit. Also, sitting closer eliminates some of the effects of side wall reflections.
FWIW.