Does anyone know what effect, if any, the position of the fletches along the main axis of the arrow has? Is it best to keep the fletchings as far back towards the nock as possible?
The further that your fletches are from the point, the better leverage they have in regard to keeping your arrow straight.
The faster they can correct your arrow, the less drag they have.
If you REALLY cared about it, measure where your arrows CG is with your fletches positioned to just clear your fingers during release.
Then move them a centimetre forward and measure how your CG changes.
Your FOC /CG should move forward. The "Center of Pressure" which is an expression that I hate using will also move forward because your fletches have.
Thus your moment arm has changed.
As you get closer to the front of the arrow, the effect will be more and more pronounced. Once you pass the FOC, your fletches will start to destabilise the arrow.
Essentially, there will be little difference, but as far back as you can get them is technically better. Your chances of seeing any real difference without a hooter shooter and very careful experimentation is so limited as to be not worth being concerned about.