Hi Guys,
The FMBs with the QS8s there was't much room for the banana plugs but it was enough. If the threaded hole for the mounting screw for the top half of the bracket was a bit higher on the back of the M 3 there probably would be enough room. The threaded hole is fairly close to the connectors putting the bracket in the way. Yeah, inverting the speaker would also do the trick but I think I'll stick with using wire spades.
/Jeff