One thing that the xlo disk helps with is checking every possility of phase probs, along with the solutions. If that doesn't seem to be the difficulty concerning l and r imaging, then you might want to consider hiring an acoustician. The guy will come in there with all the expensive equipment and properly install treatments. I just think for a really complex room situation, that that is a reasonable solution.
Severe Imaging Problem
Since getting my Aleph-3 I have lateral imaging for the first time.My problem is my room.It is the only practical way I can have speaker set up.The speakers are the same distance from side walls.The left front wall is only 2 feet long then opens to a 5.5 foot wide X 3 foot deep,floor to ceiling window alcove.The right front wall is 6.5 foot long then opens to the alcove.The alcove has windows which are treated with heavy curtains.The alcove also houses myequipment.Obviously I have much more front wall in back of my right speaker.I have side wall treatment as well as front wall.The outside (lateral) imaging is excellent from the right speaker.I couldnt be happier! The left speaker there is little to no lateral imaging.I have reversed I.C.'s