After pre-ordering the PL 100-400mm, I thought "I'll never use the 75-300 once I get the new lens". But after using it the past few days getting ready for a 7 day shoot in the American Southwest on an EP5, I decided to keep it. When used properly i is really very, very sharp. Yes, it is really not a BIF lens, but for what it is, it is small and very sharp (Mine is sharp wide open and even at 300mm - done quite a few tests on the kind of shots I will be doing, and the biggest variation is me -@ f8 at any focal length is it is very, very sharp. I was thinking about getting a 35-100 f2.8 but after looking in Light Room my 80-200 in DSLR days really got little use compared to a less expensive 70-300. I have not used the 75-300 II much since I got it as until 2 weeks ago I still had my Nikon gear. I can see a real use for this lens in my walk-a-around shooting style on one Gx8 and either the Pany 12-35 or 14+GWC1 on the other. And for flying trips, it and the Pany 14/GWC1 I think are gonna be a great light kit ranging from 11mm to 300mm with the EP5.