Ken,
When I was taught formation flying, or indeed taught others on Fast Jet OCUs one never looked at your own wintips for reference. If one could manage to formate (and AAR )in the British F4 and Tornado F3 (Bypass engines) both with a lot of throttle lag it would not be a problem in the Phenom. Having done hunderds of hours of formation in the Dominie the problem is always loosing sight, especially cross cockpit. Formation flying should be taught to ALL pilots at Basic Flying Training prior to streaming, but that is another story!