You don't save your Aetherflow for the next DWT. You use it when it aligns with DWT instead of having to wait for DWT to end. The current arrangement effectively increases the CD for Atherflow by whatever you last duration of DWT was. In the end by removing the lockout you will get more opportunities to enter DWT than the current setup that forces you to wait not only for Bahamut but also the end of DWT.
I definitely agree with your Bahamut item 1 and although I haven't thought about it as I don't PvP your second item would help the death penalty considerably. Neither however IMO change the need to remove the Aetherflow lockout. In fact it might help make up for the potential DPS loss you bring up.
