and by that I mean about 8 potency more overall, generally. Which is nothing and will never cost you a run. the people who shit and piss themselves about feather rain being better than eruption are the same people who use sonic boom over whistle/tingle/fire angon

which for reference, the latter 3 spells combined out-dps sonic boom on a per-GCD average by 3 potency and you'll use that way more so ignore anyone who tells you to pick one or the other as far as these spells go.