A Steinberg tech support guy told me:
Cubase was not designed and is not supported for touch screen devices. I apologize for the trouble that you're experiencing with the Surface. In the meantime we have designed an app (Cubasis) which is intended to be used with an iPad.
This got me curious about Cubasis, and I decided to check it out. So far, it looks like it could be useful and fun to use, and I might eventually end up using both Cubasis and Cubase as appropriate. This got me wondering if it might be possible to use them simultaneously.
Would it be possible to hook things up so that my Montage and my Roli Rise were hooked up to Cubase running on my PC, Cubasis on my iPad was also hooked up to Cubase, and I could use Cubase to route MIDI and audio from the keyboards to Cubasis?
I imagine the answer is a resounding "No," but it's an interesting enough idea that I'd like to find out for sure.
(In the process of looking into this, I ran into things like StudioMUX, MusicIO, and rtpMIDI, which might be useful if it were possible, but the whole thing is a bit over my head given my current state of knowledge.)
Good luck... I'm stressed enough with one computer type device connected, that the thought there might be some advantage to connecting two such devices never occurs to me as something I'd ever want. You can, I understand, move projects from (Cubasis) the iPad to your computer (Cubase Pro) but have yet to explore this. Let us know how you make out!
I was hoping to follow someone's well-trodden path.
I think that instead I'll concentrate more on making music. 🙂