I was glad to see that Vortex has added an ED glass option to their already good Vortex Skyline spotting scope. Just makes a good scope that much better.
Do you really need ED? That depends. If you find yourself using magnifications higher than 40x on a regular basis, you will notice a difference between a standard glass version and an ED glass version of a spotting scope. Chromatic aberration (color fringing around an image) produced in a standard glass spotting scope will rob you of some resolution and it is most noticeable at higher magnifications. Birders, like me, who are pushing the limits of a spotting scope to the extreme, love ED and other special types of optical glass.
Nice job, Vortex.