Shootout at 25mm on Olympus E-M1: SHG 14-35mm f/2.8 vs 25mm f/1.4 DG Summilux
Added to Guide to Mirrorless is a field comparison of the Olympus SHG 14-35mm f/2 and Panasonic Leica 25mm f/1.4 DG Summilux.
The Olympus 12-40mm f/2.8 PRO did not make the cut due to sever focus error, a not unusual result for which I have some acerbic words for in my autofocus on the Olympus EM1 discussion.
Shootout: Olympus E-M1 at 25mm, Boulder Logjam