I can't speak for the quality of Sony but I can give you my 2 cents on my recently purchased 70" Sharp 3D TV, 2011 model.
Do you mostly use your tv to watch cable? If so, this set is not for you. Standard definition is terrible and I dont think the HD feed is very good either, but that could be the fault of Cablevision and not the fault of the set itself.
It has become quite a maddening purchase overall. Sometimes i'll pop in a movie and it's the best picture i've ever seen (Tintin, for example). Then i'll throw in another blu ray and I see serious banding issues, especially when the screen is white/light colored with fast moving images. Same issues to a lesser extent with gaming.
Sometimes a movie will look brilliant in one scene and 5 minutes later it is plagued by banding. It drives me nuts.
It also depends if you consider yourself to have the eye of a videophile.
Every person that's seen my set tells me it's the best picture they've ever seen. I'll watch it with them and my eyes are immediately drawn to the sets shortcomings. Ignorance is bliss.
As far as picture quality goes this set ranges from a 6.5 to 10 in my opinion, depending on the source and what scene you're viewing, and luck.
Would I get this set again? I'm not sure. It was an excellent value for $2700.
If the new 80" has the exact same specs as my set but is just bigger these problems would obviously be amplified. If I were you I would wait a year and pickup a cheap 60" Panasonic now for $900 to hold you over until prices come down and reviews are up.
I would not spend 5K on a new Sharp model without asking a salesman to hook up a blu ray player and watch scenes with a lot of camera movement/fast cutting in the store. They only play ESPN at these stores for a reason, it's moderately dark with virtually no camera movement whatsoever.
Sorry for the long post hope this helps.