The Orlando Sentinel has this balanced, lengthy story about the Florida top-two initiative.
It quotes a consultant for the initiative, Steve Vancore, as saying that top-two has existed in “Oregon, California, Washington, and Nebraska.” But neither Oregon nor Nebraska has ever had a top-two system. Vancore also says top-two discourages extreme politicians, yet Washington state, which does have a top-two system, has had two of the most extrene state legislators in the nation, in recent years. See this story about Washington Representative Jenny Graham, who believes in Q-Anon and who threatened a reporter who wrote about her. See this wikipedia article about Washington Representative Matt Shea, who has called for the violent overthrow of the government.
UPDATE: here is a lengthy report on Matt Shea prepared by the Rampart Group for the Washington state legislature, for those readers who feel a wikipedia article isn’t trustworthy.