Your bilge is only dry because there isn't a problem. If you get a good sized water breach you'll want one that will pump water faster than it's coming in. You might as well. It doesn't cost much more or take up a lot of space. It will just give you piece of mind.

We had a Johnson float switch connected to our large primary Rule that had a delay to keep it from cycling if water sloshed past it. Worked well. Our bilge wasn't a dry one but after being gone for a while it was comforting to see that there was a '0' or '1'. One time we had something like 200 cycles, a dead giveaway there was a problem.