Some of you may be interested in this.
I printed out a bunch of holes from 1 to 9mm in diameter for different material at different fill percentages and measured the hole sizes using a set of 0.1 mm increment drill bits. The 1mm holes were all visibly close and were was probed with acupuncture needles down to 0.2 mm and none of them penetrated so that hole size is basically zero.
0.4mm nozzle, at standard K2 printer settings
There was no real difference for fill % ranging from 15 to 45%
Not much difference between the 3 materials tested.
Looks like it reaches a min deviation after about 6 mm.
Obviously lots more variables to test, eg vertical versus horizontal holes, other materials, printer settings etc