Upload & Sell: Off
In several decades of shooting I don't think I've actually shot at 1/8000, not even when shooting surfing, drag racing or at air shows...as of going digital I've not shot above 4K!
But I can sure see when you've got ultra fast glass how that 4K limit would be a deal breaker. And that's when the move to 8K bodies like some croppers, the 5D3 or a 1D body seems appropriate....and expensive...or use NDs.
My opting for the 6D is a simple call, move to FF and continued to use those trusty red rectangles at a lower price point...IQ looks pretty nice. As for NDs, there in my kit, used often but I'm slow as a snail when shooting, hobbyists have that option! If you shoot fast on the fly type events/subjects I'm not sure the 6D would be optimal; backup perhaps
I've not shot any city/landscapes, flowers, etc at above 4K, they're just not that elusive