I am experimenting with (call it "everything and the kitchen sink" edrum project) and intend to do a full post on the DM Dock component. I installed (and then uninstalled most) every promising app. So far, I have not tested Barbax or Korg Gadget and a couple of more comprehensive DAW apps, but,
Digistix2 responded to midi inputs immediately, so it is the only iPad app SO FAR that I saved for further testing. An early, basic function, provisional success.
However, the dock itself is finicky about power distribution with BLE MIDI and my iPad 6 plugged in, but resolved with more amperage; in my case, a cautiously watched, adjustable (i.e., 6v at 6amps, versus the Alesis supplied 2a wallwart) Chinesium psu.
Otherwise, all my experiments right now are with the DM Dock, using usbmidi to a Windows10 laptop USB3 port, with several DAW and proprietary samplers from a past life, e.g. Sibelius Garritan Aria, Kontakt after annoying updates and datamarketing nonsense, etcetc.
Works beautifully with BFD FREE.
Good luck, and Godspeed!
EDIT: you may have saved me from wasting time on Barbax...I'm just going to dump it with the other crapapps.