I guess it depends what park you really want to be at and how much you are willing to put up with.
In 2003, we flew in on the 4th, checked into our hotel around noon and made a beeline over to MK. We knew full well it would be crowded and that there was there potential for reaching capacity and not getting in. It was indeed crowded, but were anticipating that, so we were not surprised and because of that, it didn't ruin our visit. We did hear from several CM's later on in the day/evening that MK had closed the gates, reaching capacity.
We had read all of the posts that said to avoid MK, too, but we really wanted to see the fireworks in the round--it was really cool. About 60 min before the show, we grabbed a spot on the bridge into tomorrowland, figuring we were off Main Street and could get around the crowds without much problem. That wasn't really the case. The CM's had roped off areas, to stop people from entering/leaving Tomorrowland--not exactly sure why, but some ignorant people were still ducking under the rope.
The show was amazing and it wasn't too bad, until the show was over. When that rope dropped the sea of people behind us pushed us into Tomorrowland. Peoples tempers had worn thin by this time and a guy with a double stroller (no kids in it) started ramming people (hard) to get through--including me. I was 6 1/2 months pregnant at the time and he actually ran me down--my right leg got caught under his stroller and my knee was on the ground. This was very scary--DH was in front of me with our two boys and didn't know this was happening. I thought I was going to be trampled. I grabbed DH's arm from behind, pulled myself up and kicked the stroller back at this guy, yelling a few choice words. It didn't seem to phase him or anyone else. Everyone just had one thing in mind--GETTING OUT! Other than him, it wasn't too bad.
The CM's led us out the back way behind Main Street. It was sort of neat to see that and people seemed to have calmed down by this time.
Given a choice, I would still choose to go to MK again. We loved the fireworks!!! But, like I said, it depends on how tolerant you are, I think.