Keep in mind that these type of cameras and NVRs, although are spec'd and capable of these various parameters, real world testing by many of us shows if you try to run these units at higher FPS and higher bitrates than needed that you will max out the CPU in the unit and then it bugs out just long enough that you miss something or video is choppy. My car is rated for 6,000RPM redline, but I am not gonna run it in 3rd gear on the highway at 6,000RPM...same with these types of units - gotta keep them under rated capacity. Some may do better than others, but trying to use the rated "spec" of every option available is usually not going to work well, either with a car or a camera or NVR.
Look at all the threads where people came here with a jitter in the video or IVS missing motion or the SD card doesn't overwrite and they were running 30FPS and when people tell them to drop the FPS and they dropped the FPS to 15FPS the camera became stable and they could actual freeze frame the image to get a clean capture. The goal of these cameras are to capture a perp, not capture smooth motion. When we see the news, are they showing the video or a freeze frame screen shot? Nobody cares if it isn't butter smooth...getting the features to make an ID is the important factor. As always, YMMV...
Further, these types of cameras are not GoPro or Hollywood type cameras that offer slow-mo capabilities and other features. They "offer" 30FPS and 60FPS to appease the general public that thinks that is what they need, but you will not find many of us here running more than 15 FPS; and movies are shot at 24 FPS, so anything above that is a waste of storage space for what these cameras are used for. If 24 FPS works for the big screen, I think 15 FPS is more than enough for phones and tablets and most monitors LOL. Many of my cameras are running at 12FPS.
In fact, many times if a CPU is maxing out, it will adhere to the 30FPS but then slow the shutter down to try to not max the CPU, which then produces a smooth blurry image..that is the video my neighbor gets who insists on running 60FPS. He gets smooth walking people but you can't freeze frame it cause every frame is a blur, meanwhile my 12FPS gets the clean freeze frame. Shutter speed is more important the FPS as well. We both run the same shutter speed by the way, but his camera CPU is maxing out and something gotta give when you push it that hard.
You could use the 3rd stream to send to the TVs, just recognize that it is a larger network hog for it.
You then have to look at the total bandwidth of your NVR. Probably around 320Mbps, so you are at roughy 110 for the mainstream and if you run 2MP for the substream that could be another 50 or so and then you plan to stream out to 3 TVs so another 150 or so sending 2MP substream, and possibly some remote viewing and then you are approaching or over the capacity of the NVR and have to cut back resolution or bitrate or FPS.
Someone here recently was hitting that bandwidth ceiling and needed to drop down FPS and bitrate in order for the NVR to work.
Most of us once you tile up 8 cameras at once on the screen, the regular substream is just fine. Sure the substream is terrible if it is just one camera on the screen, but 8 on the screen, you probably cannot tell. You simply maximize one camera to go to the mainstream. My neighbor uses his with a projector and the substream of 8 cameras is just fine on a 6-foot tall screen. YMMV.
I run mine at D1 resolution 256bitrate and it is very responsive (especially when watching remotely) and enough for me to see if I need to mainstream a camera. As always, YMMV. Wait until you try to watch your cameras remotely with 8 cameras on your screen pushing out 2MP...laggy as crap in all likelihood. Better be on an unlimited plan.
Here is something interesting...I use OpenALPR to read plates. Somehow I accidentally was sending a D1 resolution to OpenALPR and it still read the plates accurately...
Differences between a GB and 100MB switch are not that great, so I would favor the GB switch.
