Well, you're right. It is like a perfect square and that's not optimal but you also have to be practical unless you're willing to change your floorplan.
Expect to have some significant booming between 30 and 50 Hz given your room dimensions but that can be tamed using some soft furnishings and bass traps if necessary.
I would not at all be worried about bass being killed with the two SVSs even though you have that opening into the kitchen. I have about the same volume you do, with a large opening for a very tall staircase and a single EP600 turned very low still makes the whole house rattle during movies.
One thing I will recommend you do though and you may not like me for it. Get rid of the entertainment centre. Mount a flat screen to the wall and get a low profile entertainment console instead. You will have better imaging and clarity. Your significant other may not appreciate it at first but give it time.
Also, if you can round your room corners and glue and screw 5/8" drywall (ceiling also) instead of 1/2", so much the better. And anywhere you have doors, make sure they are safe n' sound and install rubber acoustical gasket on the jam so that they don't rattle. And wherever you don't have doors, get some! Once you install your Axiom speakers, you will want to listen to them all the time without distracting others. Trust me on this one.
