Just want to clarify that neither Coral Reef nor The Maya Grill are actually Signature Dining restaurants. They only take one Disney Dining Plan credit. I know this because i've spent much of the last few months doing really in depth research for our trip in October and even booked an ADR for Coral Reef
But you may have just meant "signature" as an adjective like "iconic" or "top". In that case, i can't agree because i've never eaten at any of those places!!