Most if not all switches these days are designed for multiple uses. The one ones in my upa-1's are a double pole double throw unit IIRC and are slide, and while they are not heavy duty they should be more than capable of being switched several times a day or even an hour without any detrimental impact. I doubt they would stand up well to being switched repeatedly to and fro for hours on end.
A/B use for comparisons should be no issue at all. I fully intend to this with mine at least until I am happy with settling on one or the other input option for the most part.
My second XMC-1 is here...I LOVE THEM TWINS !!!
I have a pile of stuff that pushes out squiggly waveforms from smaller squiggly waveforms that sometimes come from 1's and 0's.
It's wonderful to behold as long as you don't let the magic smoke out.
For the most part it just all works...when it doesn't then it's time to rub a few brain cells together and soon enough it's all good to go again.