This is what Julian has to say about Logic's Direction Mixer:
" In Logic you can't truly pan/width control a stereo source unless it's on 2 mono channels - should be the same, I guess, for all DAWs
There is a plug-in in Logic that reduces width/pans a stereo image but the width reduction affects the pan (a stereo image made fully mono does not respond at all to the position (pan) control in the plug-in.
So having the very clear graphics regarding panning available in the VI would stop the need of having to insert a direction control plug-in and then fiddle with the panning on the channel pot."
I hope this answers your question.
DG