Opinions on Coach Houses?

[Nicholas Bailey]

In Chicago it's common for multi-family buildings to have a coach house behind the main building, which 120 years ago was legitimately for storing your horses and carriage, but now has been converted to an additional unit (sometimes very nice).

I worry that this basically brings me twice the expenses/maintenance. Two roofs, two heating/cooling systems, etc, with only one additional unit's rent to cover the expense. I'm curious if anyone here has experience owning/managing a property with a coach house, and what it did for your expenses.