IMHO..Given that accordions are a different animal, I always gig with a guitar back up.
Two gigs recently, one where a support artist's guitar string busted in the middle of a set...he panicked and I could see why, he had no back up guitar. I offered him mine which he gratefully accepted. Lesson #1.
Lesson#2...a lead guitarist in the side project band I'm in came to a gig with only his Telecaster...he had problems with the Tele and he ended up using my Danelectro 56 U3 Reissue, which I had in the case tuned and ready to go. Annoying thing was the lead guitarist has a Strat. at home that's perfectly fine.
Both gigs had a floor full of dancers and a house full staring at you...to walk off with the excuse 'I don't have a working instrument' will get you no more gigs and a lot of egg on the face.
I know electronics , like FR-18's , would be very stable units, but I'd personally never do a gig without a back up. You'd only get caught out once and you'd never do it again. But that principle applies to acoustic and semi-acoustic accordions/instruments.
Kirk, You're really going to like this instrument. All keys, many sounds, infinitely adjustable keyboard layout and bellows action, no feedback on stage, a volume knob, option to practice with headphones, and if you're experimenting, it can drive any midi synth (hardware or software based). Prepare your inner geek. The manual could be written more clearly, but you'll figure it out. Link #2 is an FR-18 forum with lots of good advice.