I also own the P4A/
P4P remote controller. I do a lot of testing with my drones, so I really don't fly just with the
P4P+ remote controller. It all depends on what I need to do when I'm flying.
When using Apple mobile devices, you need a cellular model if you want a mobile device with a GPS receiver. The cell service does not have to be activated. With GPS on your mobile device, you'll be able to use the Follow Me flight mode and/or manually reset the home point to your current location after taking off. If you don't need to use those features, then you don't need GPS on your mobile device. All other GPS related features use GPS data from the Phantom's internal GPS receiver.
