I agree with both replies. Our new
YiiMP mining pool offers 0% mining fee as launching offer.
We'd like to offer a future stable low mining fee around 0.5 to 1% max (we will analyse future statistics from the 2 months launch). I think that we have our jobs to pay bills and food but the aim of the mining fee is to have a sustainable pool (and not to earn money). Decentralization is one of the aim of many crypto-currencies : I prefer many small mining pools with small fees than a big mining pool that can impose its fee.
Some coins have a POS part that should be analyzed and parametrized (or a lot of code changes). As a pool owner, I prefer to take the time to analyse coins, install them on my testpool when I have a doubt, mine a block with my GPU's, check payment, memory and CPU use, pool earnings and so on. For example, I finally disabled on my pooltest 2 coins (Honey coin and another one, I don't remember the name) because I was not able to get correct payment of block mined and the coin server was using a lot of hardware ressources (POS part). Learning and testing takes time but crypto-currency is a passion for me and I cannot imagine to gain any money with a passion.
You're not new to crypto so I won't discuss about all the possibilities to have many GPU and bad payments (wrong miner for pool/stratum, wrong config, stale shares, invalid shares: erk).