Hey, so I have a lil weird of an aproach. Use audiobus for one, thats been the key to literally all MIDI and audio. You muck with buffer settings and I have an old iPad and no crashes or clicks or pops, well actually as a test I ran like ALL my apps and it tripped out.

So I monitor clean signal before the fx hence no latency on clean stick. Then I set buffer size to 256 which actually is pretty ok. Then I mix em. Usually 100 wet on iPad
*if I am going for uber stick fx and no or little clean signal then I set buffer to 126 I think and run like 2 or 3 apps, latency is minimal. Now if I was doing stick synth as well I may set buffer higher. I'm still testing this stuff. No multi tracking either for me yet.
The biggest thing is the app and how much juice it takes to run. I use tonestack by yon and it takes like zero juice, but a granular synth takes like 80%

I think audio bus is the key

Note: its possible the alexis Idock 2 is what is working so well for me. I'll keep you posted.

And don't forget to close all other apps and internet.... Sorry if I insult your intelligence

Ok so if I understand correctly you run the iPad in parallel with the Stick (in your first example) mixing dry signal and iPad f/x in the audio interface? Are you applying different effects to each side of the Stick? For example reverb and delay on the melody side and reverb and compression on the rhythm side? I was using the multitrack method to do something similar but bringing everything into the iPad...

Yeah, I can split the signal with a $2 app. I usually don't fight now I just run both sides into it stereo and use same fx for both. But I should split it more, its so fun.
I think the multi track is where the iPad is gonna max you out. I go out and record to "gasp: minidisc.

...

Which app is the 2$ splitter? Might be fun to use that into audiobus...