With 4 x 8MP ColorVu cameras you should be okay to use a DS-7616NI-I2/16P 16 Channel NVR as the total bandwidth usage for these 9 cameras will be roughly around 120-150Mbps.
Do be aware though that if you want to apply this to 4 of the 5 G1 cameras you have you will have to reduce the resolution of those cameras, this is all explained in the below thread:
Hikvison's AcuSense NVR range has now been made available in the UK. If you have an IP CCTV system set up already, but your cameras do not have AcuSense technology built into them already, then these NVRs are an affordable way to add these analytics to your system without replacing all of your...