The SDE EVH has routing and outputs for a W-D-W configuration, which is what differentiates it from the standard SDE-3000. Overall though, I think the concept for the SDE units is similar to what BOSS has done with the DM101 and RE202, which is delay pedals that are much more focused in what they do and less about versatility, which is where the DD500 gets the upper hand.
Oh, and those fucked up 1/8' TRS MIDI jacks...