Just returned from Frys. LM6700 and LM7600 side by side. I went in the menus and changed both to "standard" mode, understanding there may be some differences from set to set. Nonetheless, with both on Standard, the 7600 was by far the better picture. Very obvious, even on the in-store feed, which is not very good. Deeper colors, significantly better blacks, and better detail. During a short, black screen the 7600 was deep black, and the 6700 was quite grey. Even my wife, who went begrudgingly, agreed that the 7600 was far better, and she hates to agree with me on anything. While there, I also looked at the Panasonic 55" LED, the L55ET5, which is their passive 3D set. It's on sale for $899. I found both the LG's superior to the Panasonic in picture quality, so much so that the $300 price difference between it and the LM7600 was not even a consideration.
For anyone that might be interested, the "Dual Play" 3D glasses for gaming are $19.99 at amazon, but currently on sale at Frys for $14.99 per pair.
I'll give it a good test drive before my return period expires. Who knows, maybe I'll get lucky and they'll have to price match someone with a lower clearance price. I'll probably go to Costco and pick up the Square Trade warranty once I decide if it's a keeper.
Thanks for your input.