The affirmative action Harvard litigation discovery suggested that REA applicants had an advantage, after adjusting for hooks. The data is old at this time, but using common sense, REA is more likely to be advantageous vs detrimental. If we use the orchestra analogy, every seat is available to be filled during REA. By the time of RD, some seats will already be filled. This may be more of an issue for the “bassoon” player vs a “violinist”.
The major advantage of REA at Yale is you get sharper feedback. Getting deferred from Harvard is basically meaningless because so many get deferred. Getting deferred from Yale affirms that your application is competitive for almost all reaches.
I say REA Harvard and see how the chips fall.