Basically. I do see pieces in my community band that calls for a low C bass. They may be the same ones that have contra alto parts as well. Occasionally, I'll run across something that calls for the low bass that doesn't have any lower clarinet parts. I've told a couple of composers that you'll find the low C in places where people can afford to drop $10k on an instrument and in the next breath tell them that I could get five driveable cars for that much.