ADU on existing duplex property - worth it?

[Damon Silver]

We have a 4/2 attached duplex up and running in an Oregon college town. The property has a decent-sized lot with a carport past its shelf life. We're considering knocking down the carport and/or putting in another ADU, ideally a 2/1, to bring our comps to 6/3.

Has anyone investigated or done this recently, and have advice on the subject?  We're looking to gather info about likely cost, pitfalls, time required, considerations when obtaining financing, etc.