I know this is getting to be an older thread now, but I was doing some other changes and thought I would chime in.
I have been running 832 steps/mm on my BMG DotBit setup.
But I am also running a Smoothie board at 1/32 stepping resolution on the extruder.
So it would equate to 416 steps/mm at the more common 1/16 resolution.
That being said I recently reduced it to 815 steps/mm (407.5/mm at 1/16 stepping) because of a chronic but slight over-extrusion condition.
This is a reduction of about 2%.
I attribute this to the brand of filament I am running (Zyltech) consistently being slightly over-sized (1.77mm-1.78mm).
I love their filament and use it exclusively.
And it is very uniform batch to batch and material to material.
So rather than compensating for it in the slicer I am using, I find it easier just to tweak the extruder setting in the Smoothie board (dead simple to do).
So far so good.