Upgrade from 60ex500?

Sony Bravia HX800 55-inch KDL55HX800 1080p LCD HDTV with 3D

While you may say 3D doesn't matter now - give yourself the capability, especially since all sports will be converting this year (Sony provides most of the camera work and so that is a commitment for the future to help sell their own panels) and many more movies in the future will be 3D plus 2D - 3D can be more immersive by providing more depth to PQ (That peering into a window immersiveness) . You get LED = more energy efficient and have most future features. Adding 3D glasses becomes your choice in the future but at least it's there and ready when you decide.

The biggest regret people have is not buying the biggest panel they can afford and that fits their viewing room.

Moving down in size from the 60 inch to a 55 is not a good idea. Just ask westa6969. He has regretted every single day for the last 4 years that he didn't get the 65 inch Sharp, but instead got the 57 inch model.

As far as 3D, I wouldn't go out of my way for 3D at this point. These first generation sets need time for refinement. Right now, 3D is for early adopters.

Even though the sets have similar panels. 60(sharp) 55 samsung. With very similar performance. The issue here is that the LED backlit set will have less screen uniformity by a wide margin and the view angle on the led version is pretty bad as reported by users and reviews of all the sony led edge lit sets.

If pure image quality is your goal the ex500 smokes all the sony edgelit led sets.

Unless you are going to spend money for the local dim edge lit or local dim backlit sets 3500 to 4k and smaller sizes than the ex500 is as good as it gets.

From my observations and reading it is probably more fair to say that each has advantages but they are overall quite similar. I know that I had the opportunity last Spring to see an EX500 and 700 side by side in a high-end AV store that does not dial them up to torch mode and provides a good quality feed. I spent over an hour looking for many different features. On balance I would have taken the LED 700 but the 500 was also very good. To criticise LEDs in a blanket way one has to look very closely for things that are not normally visible.

To answer the OP I would say that the 500 is a very good set and if 3D isn't a priority well worth keeping.