I use the PPGPS app and an old Sunto X lander. Perfect combination. I would say though, that 4500 feet is high and unless your an altitude junkie most of the fun had in a PPG is had no where near as high. I'm very rarely above 2000 feet, unless I'm flying over higher ground. I don't see the need to fly at the allowable ceiling. I have a flight deck with a battery pack in it to re charge my phone, but since I've upgraded my phone the battery lasts for at least 2 hours whilst running PPGPS. its Velcroed to the deck and the only time I've had problems reading my display is just before dusk and I've forgotten to take my sun glasses off. You can super impose air charts I believe onto PPGPS as well, but I've not tried that yet. I have a HTC u11 without a barmometor pressure sensor, my PPGPS only works off GPS signal but found it to be perfectly adequate comparing it to my sunto.