Ok, so i am going to go against the grain here and say we NEVER use RD. We have kids similar to yours, they had no problem making it to the end of
MNSSHP a couple of years ago when they were 5 and 2. Everyone rolled their eyes and acted like we were crazy for thinking our kids wouldnt be like the majority and fall asleep at 9pm, but thats not our family. We close down the parks every single night at Disney. Due to that, i tend to set an alarm and get up at 8, and have to wake the kids around 8:45 to get to the parks to 10ish. We use TP to plan our entire trips, and when we went in september/october, we NEVER waited more than 20 minutes for anything. We followed our personalized plans and got the FPs we wanted and never had an issue seeing everything we wanted with large blocks of open time at the end of the evening for us to fly by the seat of our pants, so to speak. I think if your family likes nighttime and not so much mornings, i say travel the way its best for youa nd skip the RD.