For me, the issue was that after a few hours of the unit being on the camera output would start to "act up" and distort the image of the camera output. I believe a reboot of the entire fixture would solve the issue for a while.
We did have some frame tearing when switching cameras, but that was due to the lack of vertical sync on the fixture.
The most common issue is you will start seeing a cumulative lag appear in SDI.
You can daisy-chain SDI between units, but another issue can be caused if you create a loop by daisy-chaining from the end unit back to the first unit. That can cause SDI to just lock up.
