That new miner sounds pretty sweet, but Sumokin had a rough launch and I'd want to see the source for a program like that before trying to use it. Looks like a lot of work went into it. While I like free stuff, I also like to know where the benefit is to the developer before fully trusting it... or viewing the 'open source'.
The mere fact that they released the binary before publishing the source code already creates a strong sense of doubt that they could be scamming.
Visually appealing GUI programs like this miner and MinerGate's miner cost a lot of money to develop, so it's natural to suspect that their primary intent can be in enriching themselves by scamming instead of contributing to the community.
I retract my word accusing the Sumo GUI miner of being a scam, since they finally released the source code: