That was fun while it lasted, CoinPoker removed flat rakeback. Combine this with 5%, 10bb cap rake which is pretty much highest among all the sites, they might have just shot themselves in the leg.
They have similar approach as GG: advertise other means to get rakeback: splash pots and missions.
Splash pots are extra money to the pot, but that money is taken from previous hands. 0,1bb is taken from every pot, and that money is given back as splash pots. So eventually, there is no "extra" money. Yeah, a good player might win more than bad ones in splash pots when adjusting correctly to the splash. But I'm quite sure this doesn't have a huge impact. And it's definitely not a "rakeback" as you back the money that was taken from you earlier.
Missions are a nice concept, give playable tasks that credits rewards. The problem is that missions are not the same for all, nor even to everyone. They use "dynamic" processing, which means that no missions for winning players. I haven't seen a single mission so far.
So it's market high rake, with leaderboard as only rakeback.