I have DJI GO3 (older version) on my ipad mini and use it with my Phantom 3 Pro and Inspire 1 Pro.
I DO NOT plan on updating the firmware or GO3 app on those devices. It works now and the newer versions have problems.

I bought a new iPhone 6 plus to use as a backup for the ipad when needed.

I want GO3 on the iPhone but they only let you download the newest version and that's the problem.
So my concern is if I download the newest version on the iPhone and use it with my aircraft is it going to wreck my currently functioning aircraft and currently working ipad/aircraft combo?
Say I use the iphone with the copter today and then tomorrow try to use the copter with the old ipad and -booom- no longer works.

I'm willing to risk downloading the app on my phone and if it's not usuable then remove it, but if it also wrecks my aircraft from working with my ipad then there's no way it's worth it.

For those of you that don't know, some of the problems with the newer releases of the app are disconnection during flight, app crashes during flight, inferior map, failure to let you fly in areas you have permission but it says you do not, and higher CPU load causing malfunctions.

If there is any way to get an older version of the app on my phone that is what I prefer.