hello man, now the Sphinx coin has been listed on the CryptoBridge, you can buy coin on it .And you can stake it now and the pos reward is 50% of the every block reward, and the mn take another half. Now the coin ROI is very high, and i think you can invest it . And it seems that there is no shared masternodes now, but you can wait and i think the dev will add shared masternode service soon.