Lots of vlogs, blogs and reviews showing how the OM-1 does with birds and BIFs. Almost without exception these posts pair the OM-1 with the 150-400 often with a teleconvertor. Not surprisingly results are quite good as you would expect. In fact given 10 grands worth of kit, I would be very surprised if they didn't get good results. But how about doing the same exercise within the OM100-400, PL100-400 or even 100-300s which I would expect would be the tool kit of the majority of users have at their disposal.