Reasons why SMN is frustrating and difficult.

[Osmond]

~You need Aetherflow before summoning Bahamut or you'll miss 3 wyrm waves and lose dps, which you guessed it, is a dps loss

I don't remember needing aetherflow before summoning bahamut. You can cast it w/o it, although having it up while bahamut is up is not a dps loss. Remember bahamut acts each ability/spell is used so having 3 stacks up is basically having him act 3 times, more dps gained.