Yes becoming a naturalized citizen of another country presents real problems, but the OP was considering claiming a right as a natural-born citizen of Germany and the U.S., i.e., born in the U.S. and therefore a natural-born American, and born abroad of German citizens (if it could be established that all the generations since his ancestors' emigration from Germany remained German citizens), i.e, a natural-born citizen of Germany as well. Not being naturalized into a second nationality would obviate the need to renounce anything, since it wasn't his doing that made him both a German and an American. I know from a family member that this works (born in the U.S. while parents [yes, only one generation] were both still German citizens).