My nine year old sony is about to die and I need to replace it. I want to go atleast 75 inches. I have a big living room and plenty of space. I am considering purchasing the older sharp 80 inch 844u online or going to local dealer and buying the 75 inch samsung 6400 or 7100. The 8000 model is out of my price range. Of the three which would you get? Does the 7100 have that much of a better picture to warrant a $1000 increase over the 6400?