But, to me, the biggest change one can expect is on the focus of the center image (toe-in increases focus) and the left to right spread of the image (toe-in decreases the spread), such that one is trying to find the right compromise.
I think this is application specific. More toe-in will decrease reflections off the wall, so that should help with image placement. Less toe-in will increase reflections from the walls which makes things seem more spacious, but can also confuse your hearing.
If you have no wall reflections, then all toe-in does is change frequency response.