If you go by the principle of making small changes and checking frequently, filing a nut is a simple operation. You learned, as a child, how to pick up an egg, right? Your body already understands the idea of enough force to achieve the desired result and not too much force so you break it. Same principle applies. Make small changes, check the result, stop before you go too far. Easy peasy. It's genuinely nothing to be intimidated by. A bass isn't set up if the nut is too high as it has such an effect on playability. For me, a nut should leave as much clearance over the first fret as a zero fret and no more. Anything above that is needlessly inefficient. Usually, I find the nut, as a whole, is left far too high on factory instruments, not even close to being correct, and, in those circumstances, pop out the nut and sand the bottom of it to achieve the desired result, rather than re-cut each individual slot, so you may not even need a set of round files.
Plus, you only need to get it right once. I have never needed to replace a nut because of using a different gauge of strings. The nut slot should be a U shape with the break angle of the string over the nut combined with the string tension pulling the string snugly down into the bottom of the U.
Do it yourself or get a tech to do it, but make sure it gets done.