I know where my father's ancestors were living for hundreds of years. My mother's mother was third-generation American (3 German immigrant grandparents and 1 Irish immigrant grandmother). My mother's father had English, Scots-Irish, and maybe some Pennsylvania German ancestry. So I don't know if I would learn anything I don't already know by having the test done.
You might be surprised? DNA doesn’t respect National Borders, no joke. It stunned me.