I would have to say that this depends on what time of year you are going. If it is during a peak time, it might be difficult to ride a lot of rides on an EMH evening. If it is during a slower time of year, you might be able to get a lot of rides in that evening.
If you're going with the intent to ride a lot of the rides, I'm not sure how successful that would be.
If you're going with the intent just to see Epcot, walk around the World Showcase, eat something tasty in one of the countries, see Illuminations, then I think it would be worth it for sure!