The firework cruises aren't that difficult to reserve unless you are going at a popular time of the year or season. The only boat you will have trouble reserving is Grand 1 as that gets booked up very quickly.
I've been on one which was a Wishes Cruise on Grand 1 and it was really good, I loved it and the music was played on the boat as well. I'd do it again in a heartbeat
You have to be careful when booking a cruise to make sure that you are on a boat that has the music otherwise I think you would lose the effect.
If you want to make a reservation call 407-939-7529 to ask about costs and reservations.