Another issue is what to do with the black hole when it reaches the end of its life span, as they tend to explode. "Such an explosion is powerful by terrestrial standards, but not by astronomical standards", say Crane and Westmoreland, so it's merely a matter of dropping the black hole around 1 AU away from anything too important, and letting it detonate.
An AU, for the uninitiated, is an Astronomical Unit, which equates to 149,598,000 km.
On the other hand, the do point out:
A civilization equipped with our four machine tool set would be almost unimaginably energy rich. It could settle the galaxy at will.
Does that sound like a sales pitch?