For a number of years, I’ve been using the Atem iso (mini) and while good, I was always running out of input and I really didn’t like HDMI.
The new Extreme ISO, with SDI is brilliant. The inputs are much more solid and no missing particularly with input 1. And of course, the super source is lovely to use and easily programmable, as are the 4 outputs. This is a fine switcher which Blackmagic have given a lot of thought into getting right. It works every time and is very stable. I’ve never had to reboot or switch it off and back on again.
It just does what it says on the box….. with SDI.