I have an older iPad2 that I have been using with Sky Safari for the last 4 years or so (even with a cracked display due to dropping it last year at night).
I didn't like using the WiFi option to control a mount (mostly because I was looking in an eyepiece trying to center something and had to look at the iPad to find the correct slew buttons again on the iPad and then look in the eyepiece again to see how close I got to re-centering that object).
I use the iPad and Sky Safari now and then mostly for checking how is object is framed by either an eyepiece or camera's sensor (in conjunction with telescope's FR). I'm sure any of the newer and lighter iPads would be fine!
