This was kindly confirmed on KVR forum.
So, I bought Cubasis. First impressions are that it does exactly what I want it to right now in that it can import MIDI files, automatically assign micro Halion sounds, and the parts are editable.
I intend to use it to evaluate and edit SMFs on the move, and then import into PC Cubase,(meaning an expensive upgrade from Cubase 5
). However the capability of the built in fx and mixer in Cubasis appear to far exceed what I expected from this type of product.
Overall this is the first properly productive DAW product I've used on an iPad. Very impressive!