I'm pretty sure max fps at 4k is like 7fps, which should help somewhat, but they are equal to a 12mp camera, so I am sure you need some nice storage. I paid 3x the amount I would pay for 1 1.3mp camera, so if your customer wants a 4k system, with 4k cameras and 4k NVR, I am sure they have a nice budget for several 4tb hdd's.