How does Mikhail feel about working with XFS?
He barely does, to be honest. He makes most of his money these days through nefarious means (by which I mean gambling) and a little through bussing tables. He does just enough for XFS to stay on the payroll because XFS makes him feel safe, and they're the only people he really knows, and after so long with only a few people in his life, he feels clingy. So he hangs out at the office a lot more than he actually does jobs - it feels like a place he can maybe be safe and comfortable.
He needs what familiarity they provide, especially people like Kade and Lexie. Even at XFS, he often feels like an overwhelmed outsider, but at least they're a fairly small group who kind of know where he came from.
He has no particular feelings on what XFS does - he spent half of his life in such a bubble that he's kind of outside this 'use or do not use your mutation' debate. It just doesn't resonate with him. But he likes the people, and he is grateful to the people, and he likes that many of them seem to be, y'know, less terrible than the Russian mob, what with taking them down and all.