My friend Max from Spain emailed me with this interesting Echoplex, it appears to be a solid state EP-2, signed by Mike Battle himself!!!
You can see the where the tube socket holes are covered by the solid state board. It looks very much like the EP-3 circuit. Since Mr. Battle has recently passed away, we'll never know exactly what the design thoughts were but as I said above it looks like an early EP-3 prototype.
Check out the pictures of Max's one of a kind Echoplex:
