“Virtually everyone reviewing the E-M1 with firmware 3.1 who claims to have tested the focus tracking with legacy 4/3 lenses seems – on a reading of their reviews or looking at their videos – to be unable to use the camera correctly. Almost all seem to be unaware of the Continious AF with Tracking setting which is designed specifically to follow moving subjects. C-AF is not the optimum setting for this sort of photography (as detailed in the instructions) yet everyone seems to persist in evaluating the camera’s performance based on this erroroneous setting choice. Using my legacy 4/3 glass (50-200 SWD and 150/2) and C-AF+TR option, the hit rate of sharp shots on erratic movement (show-jumping, soccer, flying birds) is better than 90%. On any OM-D press OK, tap the AF setting box and turn the front input dial until you see the C-AF+TR option – it is AFTER the C-AF/S-AF+M/C-AF+M options. When you see C-AF+TR touch the shutter and enjoy better action focus performance.“ Found here: http://www.43rumors.com/a-bit-of-everything-124/ Could be worth a few tests, maybe even with other bodies and native lenses. I always thought tracking was for relatively slow moving subjects.