almost 2% is not small. oh. Not bad, he clearly raises on the commission. (Developer)
it really depends on the miner and the market condition, sometimes paying even 5%/10% of your profit MAY still benefits you. for example the D3 by bitmain has a terrible firmware , therefore usually a custom firmware was needed , and the known custom firmware by then had less than 2% fees which was very reasonable and overall profit increased even after paying the fees. however in most cases the stock firmware does just fine, also one thing that many people seem to be missing is that when dev fees are stated at say 10% , it does not mean miner will mine for 2.4 hrs straight for the dev pool and then you get the all of the remaining 21.6 hrs to your pool, it doesn't work this way simply because
1- The dev fees are time-based, they start the count from the time the miner switches to their pool till the time it swihces back to yours, there is gap in between as it's never instant when cgminer switch pools , you are looking at a quite a bigger loss as you are the only who bears those switching periods, they are small but when summed up, the became reasonably questionable.
2- The dev ensures he get's his fees asap, so assuming it's 10% , they will try to get 10% of each hour, and not straight 2.4hrs. therefore assuming you start your miner, 2 mins on your pool , then 6 mins (10%) to dev pool , then cgminer restarts for whatever reason , 2 mins on your pool 6% to his pool again !
total time for you = 4 mins , for dev = 12 mins.
of course this case will not apply 100% of the time, but the possibility is always there, dev has the right to do it this way to prevent people from cheating,but they usually don't tell you the full story.
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I tried a few custom firmware, i usually divide my miners , split them into 50% stock fw, 50% custom, let them run for a few days and them make my calculation.
i used the method mentioned above as well as Wireshark and other network tools to monitor exactly the time my miners were mining on dev pool vs mine.
there is almost 0 chance you are going to lose only what the dev states , there is always a bit to a lot extra .
so i advice everybody to do the math before trusting and settling down on a custom firmware.