Re: Is ELCI needed if AC only runs to GFCI outlets?
If you want to be ABYC compliant, you need the ELCI and I would advocate the GFCI as well.
Two different devices to deal with. The ELCI has been tested to work "better" in higher load marine environments....ie it should not trip as often as the GFCIs currently may do, especially on loaded, unbalanced systems.
Down side is they are expensive and larger devices to install, although some manufacturers are finally getting some quite small and boat power friendly. See Hubble.
Your boat, your decision...you may speak with your insurance company for further thoughts and actual events that may have lead to the approval by ABYC