I found some issues with purple fringing with the Pany 8mm, on my EM-1 MkII. Apparently the cut off filter for UV is different between Pany and Oly with the Olympus letting through wavelengths that the Pany lens does not fully correct for. Doesn't appear on all shots, most noticable with bright objects against dark backgrounds. The Capture One Pro purple fringing tool can remove much of it. If I was doing it again I'd get the Oly lens. I had a post on that here:
I was also thinking the corners were quite soft but have since decided that is due to the corner in question being much closer and falling outside the DOF. The shot in question was along a wall and the wall itself was much closer than what I was photographing.
I use the Pany 30mm macro, AF is quite snappy, noticably better than the 60mm macro, haven't used the OLy 30mm to compare. You can't take advantage of the extra magnification (1.25x) on the Oly as it focuses almost on the port glass. In fact I think the practical limit for lighting with the 30mm lenses is about 0.5x as you are getting so close to the port glass it is diffciult to light. Where they shine is for larger subjects - small fish size up to about a 300mm long subject. The working distance for such subjects is too great for the 60mm macro - too much water between you and the subject and much higher chance of backscatter, particulatlry in temperate waters where I shoot often.
Fish 20cm long: http://www.aus-natural.com/Underwater/Bony Fish/slides/Senator Wrasse 3.html
Fish 12cm long: http://www.aus-natural.com/Underwater/Bony Fish/slides/Blotched Hawkfish.html
Nudi 5cm long, 50% crop: http://www.aus-natural.com/Underwater/Nudibranches/slides/Hypselodoris bennetti.9.html
Nudis 4cm long: http://www.aus-natural.com/Underwater/Nudibranches/slides/Goniobranchus tasmaniensis2.html