I played with the demo GX80 a couple of hours in the last 2 days. Quite a nice camera. From a quick an unscientific test, I found that its IS can be effective around 2-2.5 stops with PL 15 & 25 and increases to 4 stops with Oly 75/1.8. May be around 1 stop less effective than the E-M1. I haven't tried the dual IS which should be better than body IS alone. Size and weight is nice. EVF is good if I use AF lenses but I have less confidence to MF as the evf resolution is so and so. Of course the EM-1 has a much better EVF and its bigger grip made it more comfortable to hold but around 100g heavier.
What makes me having a second thought of buying the GX80 is that I can eBay the E-M1 for 650$ including import tax but probably having to pay 800$ for the GX80 + kit lens or around 700$ for body only. Of course, the eBay GX80 will have no local warranty and I may have to bear all repair cost if something goes wrong.
What do you think, GX80 or E-M1? Please give me some food for thought.