1) The launch grid (I forget it’s proper name) is an increasingly common pattern in touch-based music apps; I want to touch the Ableton one. Especially in live performance.

2)The form factor of an iPad makes more sense in my music setup, in that I don’t need to haul podium or standing desk on stage as well as my instruments.

3. In producing tracks, most of my time is spent twiddling knobs, adjusting levels, etc, rather than dealing with external audio interfaces or doing fine grained, fiddly things with a mouse. But now iOS supports a mouse, so I could even do that...

You should check out bitwig studio on a Surface tablet! They have had an optimized Multitouch UX mode for a few years now, and it looks pretty good.

IIRC Bitwig was actually featured in the Surface launch event (I think it was the very first generation of the Surface tablet, I might be wrong though).

One advantage is that recording drum pad sessions would be more convenient on an iPad (you could just tap out a beat right on the screen). On the other hand, there's something to be said for high quality midi controllers that allow you to do the same.

For instance, an iPad would be a great place to experiment and get an idea down, and then you could bring the idea to your other, more professionally oriented tools.