I have an Ipad mini I bought 6 months ago - When I downloaSded latest firmware for my Inspire...  I was getting pixel distortion and camera was lagging...  

I hooked up my Iphone 6s and all worked great....

Anyone had this problem and if so - what device will work with a bigger screen?  Or advice on what I am doing wrong with my Ipad mini....  It worked great with the previous DJI firmaware...

Check if the "Hardware Decode" option it's on.
If it's on, and you keep getting the same lag and problems, just buy an iPad 2, like me...
It's the most cost/efficient device for the moment, until a new firmware update! ahahhaa