I am, Jill. When I use my guitar/sax rig (which is most of the time) I use the iPad Pro (12.9") for my main screen for tracks, and I have an older iPhone 6 in my pedalboard as a secondary audio source, for smooth fades, quick searches, and backup, if needed.
If I'm playing keys, I use 2 iPad Airs (9.7"), and they sit nicely on the music rack for quick access. I merge the two into a small DJ mixer and feed that into the main KB/vox signal to the house, or whatever system du jour is applicable!

The iPad Pro is my newest unit, and probably the fastest processor, although for my playback needs, I don't notice any difference in performance ... just real estate.