In this thread from the JLC forum carpenters discuss which miter saws they use to cut smaller pieces of trim. There's a good argument here for owning a smaller second saw, since most of the time you don't need the capacity of a 12-inch slider.

It was not part of the discussion, but there is also the option to go cordless for low-volume work where you can live with less cutting speed. There are a number of cordless miter saws on the market but Makita is the only company currently making a pro-grade model.