I've just got a shiny new 5K Skylake iMac and I'm using my old 27" 1440p Dell screen as a second display. It's fine for what it is, but I'm wondering if I should upgrade it to a 4K display. (I'm assuming there's no way to add a 5K display) My questions are - what will happen to the scaling on the 4K screen? Will everything just get bigger as it slides from my primary monitor to the 2nd screen? Or will it be scaled somehow to retain consistency? The nice thing with my old 1440p display is that the physical size of things is the same on both screens. And from a purely aesthetic standpoint, can anyone recommend a 4K display which sits nicely with a 27" iMac? Thanks all.