Does anyone use the dunning module?

are you asking about NetSuite invoice Dunning ?

I've helped several implementations. What's your question?

What features does the dunning module offer that can't be replicated with a couple simple workflows?

The big thing is invoice level dunning in a traceable/reportable fashion. Better invoice running across different nationalities according to their rules. Consistent setup.

Thanks yeah doesn't sound like anything we need. The only thing we did extra besides a few workflows and custom email templates was Workflow Action Script to attach PDF copies of the open invoices to the email. But I don't think dunning module does that.