That’s a shame; generally the second-hand stuff is good as it only gets used for a brief period anyway. We never bought any new stuff at all and saved loads.
Clavinets didn't have a built-in phaser (in the sense of Phase 90/Small Stone) but were often used in conjuction with one. Perhaps you are thinking of the four pickup combinations, some of which had the two pickups in or out of phase.
I tried this out today. Tracks like a bloodhound and sounds pretty great. Not as much gain as my Octabvre but tracks much better than it. The Octabvre has more bottom end and a plummier sound but the MXR is a really good octave pedal and I may well get one.
Also, just another thought: since the buttons are now at the sides, might you want to rotate the text 90 degrees (opposite direction for both so that the bottom of the letters are nearest the pedal’s edges)?
Only things I’d suggest is moving the “prog.” text up so it is in line with the “on/off” text and making sure the fonts of those two labels are the same size (prog appears bigger in the photo).