I'll take Robin's review/comparison of the Oly and Panny 25 with a pinch of salt ... somewhere in his blog, he mentioned being an "Olympus Consultant". And yes, he is indeed often partial to all things Oly. It wasn't always like this, especially when he first started.
Anyway, my take on this issue. I find the Panny 25/f1.4 more contrasty and somehow the colours are more vibrant. I also prefer the low light bokeh of the Panny. Wide open it is a little soft at the edges and if pixel peeped, yes, you might see some CA and fringing. Overall, I still prefer the output of the Panny 25/f1.4 compare to the Oly 25.
The worst downside of it is when used with an Oly body EP3 and older - the dreaded "rattle". On the EP5 and Panny's bodies, no issue.