I've been looking for a solution for a while and decided a couple years ago for the E&S EFX 3004
It combines and isolator & an EFX Send/Return. Both can be bypassed.
The EFX Send/Return is connected to my EFX Unit (Korg DL8000R Delay rack)
NB: the unit i use is one of the first prototypes Jerome build for the Zouk club so the faceplate is a bit different from the one he sells now.