I recently used my UFX in CC mode with iPad to both record (DURec) and mix a live jazz show.  Some of my troubles arose from the main performers rocking up about 3 minutes before show time (reasonable excuse- 5-month-old baby) so the sound check was the first number.  No stranger to these situations, but usually using a hardware mixer.

I'm using an iPad  Air 2.  I do switch between the normal and the enlarged screen when necessary to give me better control of faders etc.  However I do notice that some times I have difficulty "grabbing" the fader or other control.  Like wise the rotary controls as in pan, channel gain (Mics 9 - 12) and the EQ controls.  Even tapping the "spanner" or EQ buttons would not produce an immediate response.

During the first number I had to tweak the vocalists channel gain - i "grabbed" the pot, but it is quite sensitive, and under pressure the finger slipped putting the channel at full gain.  The mute button is as hard to grab as the gain pot, anyway the channel fader on that submix was zeroed and that fixed it temporarily but trying to restore the channel gain was a problem.  We eventually recovered after about 10 seconds, and I eventually regained the confidence of the band.  But there were still times throughout the evening when I had "finger troubles" and I have had to rethink the appropriateness of using an iPad for this sort of work.   (No, I am NOT going to cart along my MCUPro, and I'm not sure if it can control channel gains from it anyway.)

Two things are burnt into my brain now.   One is that - in situations like that - the 'Undo' button is the new 'Panic Button'.  Being of advanced years, my subconscious didn't work fast enough, but I will be giving it some practice befoer the next gig.  The other is that, at the back of the cupboard' I have the original ARC, and that channel gains 9 -12 can be assigned to the encoder, so I don't have to rely on the touch screen for that "touchy" (pardon the pun) task.

But there are lots of other "rotary" controls in things like EQ etc that may be the subject of finger troubles. Now my fingers are not exactly fat and stubby, and having a long time ago a close encounter with various musical instruments I still have a reasonable degree of dexterity.  But I now think that in live situations, I am wary of relying on this type of control, at least in its present state.  TMFX was developed on the predicate of use of a mouse on computer screen to control it.  Porting it to touch control on a iPad seems to me to need a bit more of a rethink in control strategy, at least in live situations.

Possibilities?  I know the big iPad Pro supports the Apple Pencil, which may be able to act more like a mouse, with a finer contact point, more reliable "grabbing" and better control over movement.  The big iPad pro is inconvenient for me (not to mention expensive), but it is rumoured that the new iPad Pro 2 (10inch format) will support the Apple Pencil and maybe this will work better in these situations.  But it's Apple - who knows?

Another possibility is to make the controls even larger.  If one opens up the "spanner" or EQ panels, it would be useful it there was an option when opening these types of control panel,instead of sliding across, it would "pop-up" to the full height of the display; the larger area and increased size of the controls would make individual controls easier to operate.  The panel would of course then revert to the normal size when closed.

Controlling a live show from an iPad like this puts me in mind of Samuel Johnson's remarks when he observed dogs trained to walk upright on their hind legs: "One marvels not so much that it were done well, more that it was done at all".  Yes we can mix a show on TotalMix FX on an iPad;  but are there any further optimisations possible to do it well?

Maybe there are others who have attempted this and encountered limitations in this regard; others may have been wildly successful.  Maybe I just need a little more practice in this regard.  In all cases, swapping ideas is always useful.  Let's see what we can find?