It seems to me that whether you have EQ or not, by shifting out of the "sweet spot" much is going to change anyway just by being off axis.
Even if one were to have the room treated professionally with something like "Echo Busters" and "Bass Traps", wouldn't it all be tailored to the sweet spot and much would change in this scenario as well? I guess we can't have our cake and eat it to.
But the great thing is that, in my castle, I don't have to worry about changing listening positions because the sweet spot is
MINE baby, all mine!
.
I've enjoyed using both the Pioneer MACAA and the Yamaha YPAO and have found that they both made a dramatic and useful difference but it's not perfect. Remember, this is just my 2 cents worth, and it's only what I've experienced
in my room, in my sweet spot. Take it with a grain and listen for yourself if you are thinking about buying these products.