Mine are in a corner and about 25-30cm away from wall. I've found that using just the outer core of the bung is fine (after experimenting with no bung or the full bung). I can't move the speakers further away from wall, and banned from rearranging the room as I'd like to 🙂
Pic is here: http://www.whathifi.com/forum/your-system/bw-cm8
I've found the CM8s great with both a stereo Cyrus system, and also as part of a CM-based surround system via the pioneer LX53.