That kind of shunt diode protection does nothing to limit the fault current. If you connected a 9V batter backwards, you'd smoke some traces on the board. Most pedal power supplies limit the current to a safe level. Any diode rated for 1A or higher will suffice. That includes the 1N4xxx series, 1N5806, 1N5817, etc. Small signal diodes like 1N914, 1N4148, BATxx, could fail before the power supply goes into current limit. I prefer the series protection that PedalPCB employs.