Well there are a couple of statements here such as "The 4770k destroys it in single core performance" that stretch the truth so much they are almost the opposite of the truth. A little better in most things yes, but far from total destruction.
In-fact the 980X still does better in video creation (the main reason many of us bought it) than the modern day 6 core equivalent or predecessor the 4960X.
That said, I make it a rule never to buy old tech which the 980X most definitely is. If you were buying it to replace another CPU on an existing X58 mobo i'd say go for it, $200 is a good deal, but that's not the case here.
As the tech for CPU's improve so does the tech for motherboards (and everything else). The newer LGA 2011 motherboards have many improvements over the 980X's LGA 1366 (X58) motherboards not to mention the limited options you would have for buying a LGA 1366 mobo.
Unless video creation is your main thing stick with new tech.