I would say don't let the revenue be your deciding factor. Build the idea that you enjoy the most. If you'd really like to try both then go for it.

Just be careful to validate your SaaS business idea early and often, as it can easily become a much more complex project than what it sounds like you've put together on the AppStore. Also, something critical to keep in mind here is how you will obtain customers. You mention that the market for this app isn't very used to working with online tools, how will they find you? A benefit of the AppStore is that it can provide a lot of the traffic on its own. With a SaaS app you need to generate traffic yourself.