TOPIC: DJI Drone & HIP Mobile

I need some help with this decision. I just got my DJI Phantom 3 Advance drone or quadcopter, depending on the term you like to use- www.dji.com/product/phantom-3 . I will use it for roof inspections. The question is what device to use to fly the copter and also load HIP Mobile. Currently I have the Samsung S3, but it is slow with the copter so I am going to upgrade. Below is a list of recommended devices from DJI. I was thinking of an Ipad, Samsung S5 or the Samsung tablet. The tablet is not on the recommended list but DJI says all that means is they haven't tested it yet, but have heard it works well from the flying community. I am not sure on the Ipad because I hear it is slow and you can only run one app at a time. So some help would be appreciated.

iOS: iPhone 5s, iPhone 6, iPhone 6 Plus, iPad Air, iPad Air Wi-Fi + Cellular, iPad mini 2, iPad mini 2 Wi-Fi + Cellular, iPad Air 2, iPad Air 2 Wi-Fi + Cellular, iPad mini 3, and iPad mini 3 Wi-Fi + Cellular. This app is optimized for iPhone 5s, iPhone 6, and iPhone 6 Plus
Android: Samsung S5, Note 3, Sony Xperia Z3, Google Nexus 7 II, Google Nexus 9, Mi 3, Nubia Z7 mini

How soon are you buying? IOS 9 will add multitasking.

I am not in a rush. Is IOS9 for the Ipad and which version of Ipad?