The 55DT50 sold by Amazon Warehouse Deals is worth considering. New ones are sold for almost 1500 on Amazon but like new ones are sold for about 740.
I have had both E50 and DT50. I bought a 42E50 earlier this year and sold it a few weeks ago because it was too small.
Then I bought a 47DT50 and returned it. It was still a bit too small and I was unhappy with the black level. I thought about getting a 2013 model but then I realized that new models will be very expensive and there won't be many warehouse deals.
I will probably pull the trigger on the 55DT50. I will have to put up with the light black level...but then almost all LED TVs suck with black level.
About picture quality:
(1) E50 is a notch above entry level. Picture quality is somewhat reminiscent of DT50 but is less clear and sharp. DT50 has the Clear Panel Pro which allows more light to pass through.
(2) E50 has a lot of soap opera effect at any motion setting. DT50 has no ghosting and no SOE if motion is set on weak. There is some natural judder that makes movies realistic.
(3) E50 has better black level than DT50. But once you use a tiny bit of dim light, the blacks of the DT50 will be black and the picture is stunning. This is true for all LCD/LED TVs. Black levels suck unless you use a little lighting.