We'll be there for a long weekend, and we're doing MNSSHP on the 21st. We went on the 30th last year. It was crowded at points during the day, but it was never like it is in May.
The actual event was not too crowded at all. Since we have annual passes, we were already in the park that day. They passed out the bracelets early so we didn't have to wait in line. They pass them out at lots of locations. We picked ours up at Tortouga across from Pirates; same for MVMCP in December. What I really like now, is that last year they started enforcing the wristbands. They closed all the stores and you couldn't get in without the wristband, and they had cm's hand to hand across the walkthroughs to each area checking for wristbands or you could not get through, so this cut the crowd down a lot. They used to allow people to stay in, but they wouldn't let them on the rides like at afterhours, but this was so much better for those of us who paid that extra money for the event. It cut down on the parade crowds also. Tip The 10:30 parade is far less crowded than the earlier one and an absolute must see if you like zombies and such. The Villians show in front of the castle a little while after the parade is also a must see.