I've been using the Dynamic sound group saved into a prefab and have noticed 2 small issues:
1) The little speaker icon next to each sound group on the Dynamic Sound Group Creator script doesn't actually preview the sounds. But the speaker icon in the actual sound group "Dynamic Sound Group" script works fine.
2) Changes to some, possibly all or most, of the properties in the Dynamic Sound Group creator script don't save unless I hit Apply (prefab control at the top of the inspector). I know that they wouldn't normally save to the prefab unless I pressed apply, but they also don't save to the instance of the Dynamic Sound Group creator in the scene (in editing, not runtime). Not sure if this happens all the time, but I've gotten into the habit of pressing apply everytime I change a setting.