Waiting for mining to be somewhat un-nerfed, I did some research into how the crafted refiners perform in VU7.6
Basic conclusions:
-Decay is proportional to the amount of finished product.
-Refining smaller amounts, may as with many other things give unrepresentative results due to rounding...
The COS calculations seem to be messed up at the moment.
All skills are ignored, but QR is still taken account of.
So until this is fixed, stick to high QR BPs to maintain excellent chance.
/Guleth