Stay with the 703 and save the money. With a solid slab behind, 705 is a waste of money.
I didn't actually hear a difference with the rear traps in place. It might be because the waves are so bad in the room, that 95% of the bass is in the front of the room, and as you walk to the rear it drops off until it's non-existent. Weirdness. I'm hoping the front traps will make a difference. I'm going to do some before / after waterfall charts to measure the change, but I'm waiting until the traps are done so I can ensure that the volume and mic placement are identical.And how is the sound? I suspect it's helping your bottom end tightness and dialog intelligibility.
Also, have you insulated above the drop ceiling? That'll give you some nice broadband bottom end control too.
To be honest, I suspect they are working out quite well! I added two first-order reflection traps on both sides of the listening area, and that's the only change I made. I could still use *more* traps I think, as the bass isn't as smooth as I'd like it to be as I slide across the sofa, but in the prime listening locations I'm happy with it.Any further updates on how the superchunk traps are working out? I was thinking about building some myself, but ended up building two 4in thick panels with OC703. I was not blown away by the difference in bass performance when I put them in the corners. The biggest improvement in sound ocurred when the traps were directly behind my speakers - probably due to blocking the first reflection. Bass didn't improve until I moved my sub out of the corner and placed it closer to my seating position