I am looking at either of these lenses for taking photos of aeroplanes as they take-off or land from my nearest airport, and maybe from others if I decide to travel. I have used the 40-150 on my E-M5 and whilst I was happy with the results, a little bit of extra reach would have helped. I've read a lot of posts and it seems in a lot of cases people suggest the Panny lens for Panny bodies, and the Oly lens for Oly bodies. Having said that, the 100-300 can probably be picked up for around $50-$100 less based on local used prices. It's not a lens I'd use frequently so saving a few dollars helps. That said, the Panny 45-200, albeit shorter, is cheaper again. Or, as an even cheaper alternative. would I be better off adapting a legacy zoom lens and using manual focus?