When you're hopping from one call to the other, having the ability to quickly drop and join the next one [EDIT: with audio from my phone] is a big win
That, the global Alt+A / Alt+V for the audio / video mute toggle respectively, and the "hold spacebar to talk" hotkeys make it the clear winner from an UX perspective IMHO, even if that X isn't really perfect
At the end of the day, most calls are virtually lag free so I care more about my ability to efficiently interface with the app than I do about a perceived streaming quality [EDIT: except, of course, for those participants who don't join the audio via their phone, as their voices inevitably suffer from some lag and distortion]