Problems in the dating of the change in Claudius Pulcher’s name came up in a discussion, perhaps a book discussion chat. Today I found an article from 2002 on the very topic.
Clodius / Claudius
Andrew M. Riggsby
Historia: Zeitschrift für Alte Geschichte, Vol. 51, No. 1 (1st Qtr., 2002), pp. 117-123
Claudius Pulcher’s name changed before his adoption. His adoption was in 59 B.C., but Cicero refers to him as Clodius in 61 and 60. In addition, the plebeian who adopted Claudius was not named Clodius, but P. Fonteius. In addition, the Clodia sister(s) did not undergo adoption into a plebeian gens. Riggsby says the idea that Clodius took the name for its populist appeal doesn’t hold, either because the name Claudius was used by plebeians, too. However, there is a related populist element. The pronunciation of au was different from o and the o was associated with non-elite speakers.