I created this top filament mount to because I noticed filament shavings on top of my extruder. I took this as a symptom that the motors were pulling on my spool and I was getting an inconsistent flow of filament into the extruder. To fix this, I mounted the filament where the outside of my roll was right over my extruder. This will allow the roll to naturally unwind and put minimal force on the x-motor.
EDIT: I have added a picture of the double setup so the spool will mount over the center of the printer. The spool will no longer be pulled by the left side the the x carriage.