Just purchased NVR5216-16P and used it for couple of days with one 4231EM-AS. I added 4T purple drive. Here is my experience.
Setting up the NVR was easy. It's webui didn't work in firefox but worked in IE (win 10) in first try. Also smartPSS (download from Dahua website) worked perfectly. Also the mouse connected to NVR with TV via HDMI worked perfectly. So there are three ways to do same thing.
I connected NVR to my network (connected via ethernet to a wifi router). Connected camera to NVR via ethernet (PoE). I was able to access NVR webui from my laptop with wifi connection. Smart PSS running on laptop also connected easily.
I was able to setup camera's motion detection and IVS including other camera settings right at NVR (use any of three method, WebUI, SmartPSS, Mouse+TV). I was also able login into camera's own webui from laptop via NVR web ui. Just select the camera in IMAGE->Registration and click on IE icon. I used continuous+MD(motion detect)+IVS recordings. I didn't see any lost frames. All IVS (trip wire) triggers were legit and camera didn't miss any. I have to fiddle with motion detection area, sensitivity, threshold etc to get it right (still not perfect).
Play back is very easy. I can click on timeline. I can zoom in and out in timeline. I can also select (unselect) checkbox to see only MD or IVS video. WebUI allows export to .dav file, but SmartPSS allows to export to .avf, .mp4, .avi etc. I exported to .mp4 and it played in all the players (s/w and blue ray) i have.
The fan of NVR is loud if your room is quiet. It kind a makes noise of laptop fan (like when laptop is doing serious number crunching or video processing). I put the NVR in TV entertainment center which is open from back but closed from front. Then from 10 feet, I could not hear a thing. Anyway I have moved NVR to basement, where it is cool and in open.
My experience of NVR is pretty good. I will not go with blue-iris, but to be honest I have never used
blue IRIS. Maybe the newer NVR software (14 aug, 2017) is more stable and has brought more functionality than people here have experienced.
No I am not working for Dahua, you can see that from my previous posts from last 3 months. These is my honest opinion. It took some while to understand WebUI and all the functions. Still I am not sure of all functions, but I am comfortable with 80-90%, all because of support and information from this forum as well as other sites and also Dahua docs (on their site).
Hope this helps.