This might be a bad or brilliant decision, but I'm leaning more toward a questionable move. Based on the interviews I saw with sayf, the guy has such a huge ego, you combine that with less with another huge ego. Seems like a trainwreck.
Being an IGL is more than just about being tactically sound or having good game sense, its about having a strong personality and having that voice that players listen to. considering the players that are joining Vitality I am sure that Having a player like sayf igl would be a good thing.