I've used a Kemper for over 6 years, have a Stage and traded the toaster for the FM3, and was involved in early testing of the Kemper iOS app on both the Stage and toaster. First thing; I am not aware of the Stage having bluetooth, it has an internal WiFi module that can connect directly to iOS as such. It works extremely well but for one thing; I haven't seen where you can load or download profiles or Performances with it. But as an editor it is extremely stable and fast due to the WiFi connection. Also if you have your iOS on a network, and you plug the toaster into that same network with a cable, the Kemper iOS app can control the toaster. You could also use a wireless hub on the Kemper and connect it that way. But the key to the Kemper's success here is its ethernet connectivity.
I recall a Line 6 rep on TGP saying they had to limit the use of their iOS apps through a standard or BLE midi connection as it is just too slow to transfer a lot of data. To my knowledge the FM3 does all its external editing through midi over USB, which can be faster than standard midi.
I'd guess from all of this that the reason we haven't seen a Fractal iOS app or stellar performance from FracPad is the standard non-USB MIDI comm speed (50kbs IIRC). But since the FM3 can talk comfortably via USB to iOS (class compliant perhaps?) maybe there's something Fractal can do with that.
Does Fractal offer any iOS apps at all? That appears to be its own ecosystem that perhaps they aren't into yet.