I'm almost done building my m43 kit. I started off with the P20 added the P14 and now I'm nearly ready to finish it off with with a short telephoto to complete the class 28,40,90 set from the Leica CL/Minolta CLE era. That'll provide me with three useful focal lengths in a small kit and then I'm done buying stuff for the next few years. The first thing I thought of was the O45/1.8. I've had that lens two or three times over the years and always thought it renders nicely. The build quality has always struck me as super cheap and plasticky but for around $200 used its worth considering. The other sticking point for me is the veeeery long minimum focus distance. To me it feels like It's about half a mile. Typically I like to get close (or have the option to) and the P14 and P20 do that wonderfully. When I found out about the P42.5/1.7 I thought that it would be the answer given its nicer build and close focus ability but I find myself impressed by the O45 images and not so much by the P42.5/1.7 images I have seen. I can't tell you what it is because the Panasonic allegedly has better sharpness and contrast but time and time again I find myself drawn to the Olympus 45 images, maybe it's because there are simply more O45's out there. At the moment I have an old SMC Pentax 50/1.4 filling in but that's a short term fix as I really don't care for the experiencing of shooting adapted lenses with the my E-M10. At some point I am going to want to pick up an AF 45.