I'm using a Nuvinci with a SBP shifter kit, and I've read other posts from people here with a wide variety of other internal hubs and shifter kits. Doesn't seem like the presence of a coasterbrake in these hubs would change anything. But you would definitely lose your ability to actually brake using that coasterbrake - when you try to pedal backwards, your cranks will just freewheel, never engaging the brake.
Having said that, here is a post from someone who tried this combination and thought it was too jerky when shifting: http://motorbicycling.com/f3/anyone-...peed-6919.html
Whatever you decide on, let us know how it works out!