Hi all. I have the 4/3 14-54 and have the hance to get the 4/3 top pro 14-35 for 800 euro. Has anyone used it on Olympus bodies like em1 and can tell me how af works? Is it worth buying it if I already have the 14-54 iq wise? Would the iq be the same or much better on the 14-35? Any feedback would be appreciated.