To be more insight, I'm not the expert, please correct if i'm wrong. But based on my research, Sprouts+ maybe the first fork of eth with POS. Since there are not many clones eth out there and eth just supported POS with their Casper release this November. And they even haven't moved over full POS yet. They just announced their Alpha Casper Testnet recently ( I'm not sure if this is related with sprouts+ testnet or not ). So it must be tough for the sprouts+ dev team to clone eth here but very promising.