I agree with PPs. If you want to do FoP, definitely get that FP+.
For our November trip, I have 3 FoP FP+ and none for NRJ. I feel like we'll want to ride FoP more than once, and NRJ just once.
My plan is to arrive at 9 for AK. That way, the FoP hordes will already be there, and we can have a leisurely walk to NRJ. I figure it will be about 20 minutes at that point, and that sounds great to me!