Your room looks bigger than mine Mojo, maybe it's the bow window, or maybe it's the lighting. But in my case I think using the long wall would limit how much of the room get good sound; but who knows, maybe the LFR would reduce that problem too. (Nice room by the way! And I didn't know you played an instrument. That automatically gives you more acoustic cred.)
FWIW, Axiom did say the LFRs would be better; but it was more because they are LFRs, not because of sizing problems.
I've noticed all the discussion of the on-walls elsewhere, and it's caught my eye. I love listening to music in all-channel stereo, and that's because of the enveloping 3D effect. But of course it's also a little acoustically inaccurate. I'm hoping the LFRs gives me the enveloping feel, but with more accuracy. But if that fails, I'll be looking to add on-walls (or maybe in-walls) in the rear. But that's well down the road.
