Well, if you want to find out, mine against your own pool. Its not like there is not a pool operator posting here for some reason...

The fee is 2.5%, this is immutable and hard coded. For S9, it is 2%, also hard codded and immutable. There are no choices of changing this.

If you use groups and assign fixed ratio, you will notice there is a hidden group always taking 2.5%, so you only have 97.5% available to split. Its not 90%, 95%, or whatever random fake account of the month decides to invent because they didn't like point the fact that all other firmware infringes cgminer license while Braiins doesn't. Too bad that pool operator doesn't care and prefers to join the badmouthing crowd without proof, as usual.

Farm proxy is another project, and has a different license. It has no fees.