Using your Mini and AUM is absolutely possible with a modern iPad. See here:
While the Demo is with a Play+, the same is true for the Mini as well as the Tracker+
The one thing that is currently not possible, is to send audio back for sampling via USB only, but there is a wish for it, so go vote on it:
And there is a tiny little workaround for now, that only requires a short 3.5mm to 3.5mm cable: