Apologies in advance, this somewhat overlaps with my previous this-or-that, where I tried to cram too many decisions into one post. On the other hand, this seems like a pretty general question, since these are the only long zooms native to m4/3. I'm looking for a wildlife lens. I have a budget of approx USD500 (I'm in Canada, fwiw). TBH I don't really know what kind of wildlife I'm looking at. For static stuff at medium distance I have a 200mm legacy MF, but that doesn't seem too practical for moving animals and or moving vehicles. I already have a 60mm sigma 2.8, so the extra focal range of of the Olympus lens is maybe not as compelling as it would otherwise be (although of course changing lenses is an issue). From the completely unscientific method of looking at people's posted samples I was pretty convinced that the P100-300 gets nicer results at the long end. On the other hand it's heavier, seems to be a bit more expensive, and some techical reviews (e.g. DXOMark) claim the Olympus is actually sharper. The EM10 IBIS is ok, so I probably don't get much benefit from the OIS in the Panasonic lens.