I currently shoot with my EM5 (1st version) with the Panasonic 100-300. Not exactly the performer in terms of tracking moving objects but I've been working it. Em5 doesn't track well and 100-300 is a pretty dated lens (good value.. and compact). I've been considering the EM1 (with its phase detect sites) but I've been hesitating (prices are also coming down). Now the Panasonic 100-400 is on the shelves it has me wondering. Which combination would have have a significant improvement from a AF standpoint: * EM5 (mk 1) + new Panasonic 100-400 * EM1 (mk 1) + old Panasonic 100-300. I guess I'm trying to figure out if the bottleneck for AF performance is really the body EM5 body or the slower 100-300 pany lens.