We do mostly a Motion detection for 30 seconds as these cameras are monitoring our front gate entrance traffic.According to the network / bandwidth spec your model has 40 Mbps in and 80 Mbps out for your 16 cameras ( 80/16 = 5 Mbps per camera )
I'm not sure how blue iris is set up so i can't say for certain if this is enough i.e. does it record sub streams and then record main stream when motion is detected or just record main stream all the time?
For reference i know my dahua 5216 has the same outgoing limit of 80 Mbps and it's a decent recorder.
I'll let the others confirm my thoughts and my maths lol