With dead man’s switch I mean that equipment is automatically turned off if you don’t react. (The corresponding bridge setting is called “Turn off the equipment if members don’t interact…”.)
If that option is enabled for the previous bridge model, you have to swipe your card regularly. On the new bridges, you can also press the 
-Button whenever it starts blinking/beeping. That’s great when you switch on equipment using your phone, because it’s cumbersome to get your phone out and scan again whenever the bridge starts blinking.
But the new button also makes it easier to keep multiple machines running, which might not be what labs want.