There is actually a huge difference between the Seiki 55" and the 65" in my opinion. When I went to 4K Studios in Hollywood, they had a 65" there and that is what ultimately inspired me to get the Seiki. The 4k content that was streaming looked excellent on the 65".... unfortunately, the wall I decided to put my TV on can't take a 65" but it was my first choice!!!! The 55" will have to do for now, but there are much better 4k TV's out now and ULTRAFLIX IS A FEATURED APP ON ALL OF THEM!!!!