All true Olimpus have in camera focus so do not rely on lenses with motors.
Had a look at the Olympus OM EM1 looks a good camera to me but a little expensive.
I only seem to use my SLR for bike racing and want something lighter I will have a look at the new OM 5 or whatever thay call it and decided then.
Haven't got any fast lenses so that's not a problem but focus speed is as is good image quality.