That is your issue right there. Every new OS comes with issues, and we are waiting for OB 1.2 that has the fix for the new USB drivers in High Sierra. I find that my AR MKi bends occasionally with just the USB plugged in, without playing it through Ableton.
Also, I upgraded to Live 10 and the reliability has increased slightly. If you have $80 and are looking for marginal improvement, the intro version of Ableton 10 wouldn’t be a bad thing to have for your show (though I don’t know how many native instruments you use). This might have mixed results at the moment though, as there is variance across systems. But going forward (especially OB 1.2 release) having updated software should alleviate certain issues, as developers always try to use the latest version.
In all honesty, OB doesn’t currently stand up to “mission critical” uses. You might be better off finding an analog mixer and some cables if you want to sleep well the night before your show.
If you’re just using the AR and the A4, I might recommend ditching the laptop/mixer and just plugging the AR into the A4 for the effects (not vice-versa - the AR input circuitry isn’t great). The A4 inputs sound great, and I’ve never been able to get as nice of a sound from my Komplete Audio 6.
I guess it would ultimately depend on how you are sequencing it/whether you are using Ableton’s effects, but I’ve had a lot of success using daisy-chained Elektron boxes. Currently I have a Rytm, Digitakt, and Digitone running through a Yamaha MG06X mixer with the Digitakt running to the input of the Digitone and the Rytm on the main mixer input. The sound is pristine with and there is zero latency.