vMix has the ability to be an excellent tool for churches and houses of worship. Unfortunately, it needs a lot of careful configuration and hardware selection to make it usable.
This is my system layout right now:
Some of the TVs are over 100 feet away. At 1080i/60, I'm getting a total delay of 70 ms between the camera and the TVs if I bypass vMix (red path), and 140 ms if I go through vMix (green path). Most of the additional delay in the vMix path is due to the video capture device, so vMix and its output are a very small factor.
The equipment I'm currently using is:
Camera: Sony HVR-V1U
Video capture: AVerMedia ExtremeCap U3
PC: i7-4770 / GeForce GTX 660 / 8 GB RAM
SD card recorder: AVerMedia Live Gamer Portable
HDMI splitters: cheap Sewell splitters from Amazon
HDMI switch: IOGear AVIOR GHSW8141
SDI splitter: Matrix Switch MAHDD16
HDMI to SDI converter: Lenkeng LKV389 (US$125)
SDI to HDMI converters: Lenkeng LKV368 (US$45 each)
Camera remote control: Bescor MP-101 + Expedition Electrics USB Pan Tilt LANC Controller + Logitech F310
vMix remote: Raspberry Pi + Python Script + wireless numeric keypad
vMix output is through the HDMI secondary output on the video card and the Fullscreen feature of vMix.
Our sound is sent to the ceiling speakers directly from the audio mixer, so it's not in sync with the video. But 140 ms is barely noticeable, and I'm mostly happy with it.
I haven't been able to get the same results with 1080p/60 because the cameras I've tried have added at least 60 ms more delay, which becomes very noticeable. And in the process, I've learned that many devices along the path can introduce delay.
It would be good to have hardware recommendations for a vMix live production system that keeps latency as an important focus. I can add my own experiences, but it needs input from others too.