We used FP+ for MSEP and then stayed put for the castle projection show and Wishes. I wouldn't hesitate to do it again. It was AMAZING!! We didn't line up ahead of time like is sometimes recommended including in the blog. We got there around 10-15 minutes before MSEP was scheduled to start and we easily got a spot right up at the rope (which they remove right before the parade starts). DD13 was in a wheelchair and our autistic DD16 had plenty of room. There was nobody behind us. I guess the number of FPs for MSEP is well managed so that there's plenty of room in the area. After the parade, there were a lot of people swarming towards the castle for the projection show but not moving was the best thing for us. Trying to move through the mob with a wheelchair and an autistic teen would have been a nightmare. For some reason, people crowded really close together on the road but not so tightly together in the non-road MSEP viewing area (there were a lot but not nearly as much as the road). DD13 couldn't see the bottom of the castle because she was so low (I crouched several times and put my head right beside hers to get an idea of her view to see if I needed to shift some for her sake). It really was only the bottom that she couldn't see and the rest of us had a great view. Nobody seemed to move around after the projection show while waiting for Wishes, us included. We had a great view of Wishes from where we were. Some people feel that it's too close to the castle but I thought it was great. It was LOUD though. DD13 who typically doesn't demonstrate auditory sensory issues kept covering her ears. DD16 who does have some auditory sensory sensitivity (though these days only when it's unexpected which would not be the case with a fireworks show) didn't even flinch once. I liked that we were facing the fireworks directly rather than from the side like at the rose garden. I will say that getting out, even to head to Tommorrowland rather than towards the gate, was a nightmare with the wheelchair. If I was to do it again, I'd just stay put longer.
Anyway, if we wanted to see Wishes again, I'd go the same route and book the MSEP FP and stay put rather than booking a Wishes FP.