In the current version of Superior Drummer 3 (Superior Drummer 3 plug-in version 3.3.6 (build 35757) [64-bit VST 2] / Standalone host version 3.3.6 (build 35757)) :
In the “grooves” tab : if the metronome is turned on, you can hear it when playing back MIDI tracks in the bottom, BUT you can’t hear it if you’re listening to grooves directly from the library (the available results in the middle of the screen).
We should be able to preview grooves from the library while hearing the metronome.