Well.. I was close lol. EFs can still ping regardless of the sensor. My old stock fairmont pinged occasionally.

Probably best to run it with the AU knock sensor, then pull the fault codes from the EF ECU.
There is a code for the knock sensor, so if it's not compatible, the code will come up.

Other thing is, if there is a compatibility problem, won't the ECU substitute a default value, making the system 'appear' like it's working ??

Nope, My ef just pinged VERY badly with any load constantly. They run alot of timing. EF sensor in the pinging was gone. With a slight ping here and there they are designed to do that to ensure optimum timing.