I've read that gear reduction actually makes retraction less precise, due to backlash in the gears. I'll look at gear reduction, and I'll probably end up making a geared and un geared version of my extruder. To be honest I quite like the idea of a double sides drive, it looks cool at the very least and the thread I linked has some evidence that it helps the extruder keep up at higher speeds, plus it would add a bit to precision since you've got a more secure grip on the filament.

My main question at this point is whether a geared or direct driven extruder can extrude at a higher rate, I understand geared has more precision for obvious reasons.