London calling
My understanding is that to be included in the FTSE 100, you need to be a domestic corporation, thus the plc.
Any tax treatment of dividends will be very small beer in comparison to the expected benefit of not only being in the Footsie by year end, but just generally being in front of an audience that doesn't automatically squirm when "Africa" is mentioned.
Some time ago it was trial-ballooned that Kinross would follow, possibly as part of an asset split-up. Might be worthwhile having a few shillings on that horse if the Brits like the colour of Endeavour plc.