I bet it's a lot shorter than the delay involved in me using the touch sensitive not-buttons on the front of my monitor to switch inputs, which is what I do now. :P
It also does 4K at 60 Hz. You can switch via the keyboard (uses scroll lock as a shortcut). It has worked flawlessly for me and is only £86.
The only real downside is that it is yet more wires, and it can only switch one video signal. If I had two monitors I'd probably go with this guys solution.
I suspect a USB 3 KVM switch does not exist. His solution also doesn't help if you want to switch a USB 3 device between computers. So that isn't really a con.