I have been multiple times and I don't think it makes a difference, since the closing time is the same whether they have EEH that day or not.
Remember, you are welcome to stay in Epcot during EEH even if you don't qualify for it, you just can't ride anything, but you can walk around, shop and eat (only few shops remains open).
If they have any other event that needs to shut down the park earlier, usually it is less crowded (usually).