I have tried coinmine vs a couple of the other pools. 1 rig of 3 R9 290s 3 days each pool rotating over a couple of pools.
I get slightly more profit from a couple of the other pools than with coinmine. not sure why.
Coinmine should increase fee to reduce its hashing power. With more than 50% hashing power belongs to Coinmine, the price of the coin cannot be increased.