Its not as bad as I've seen but the 25db swing between the 50hz peak and 90hz null indicates you can really improve bass in room. Your first concern should be to eliminate that peak at 50hz. If you have the capability try crossing at 70hz first and then switch phase to see which setting smooths response with the mains 10hz up and down. I'm assuming you have the sub bypassed and are crossing at the processor. Once you have that peak tamed keep raising the crossover point, up to 90hz or 100hz, if you have to and see if the null disappears. You may just have to live with the null at 90 hz but traps in the corners should help raise it.
You can see the effect of room resonance from the periodic nulls every 25hz from 90hz to 100hz. Acoustical panels at the first reflection points would help somewhat. I know you like the imaging but experimenting with distance between the speakers and between the M80s and the wall may also provide some benefit with response. If they were my speakers I would move them out somemore but let your ear be the judge. I see you are constrained where you can move the sofa by the pillar so you will have to find the best compromise. Looks like you have a few hours of fun ahead of you.
