I have 2 screens as well. My left monitor is the primary and I have the active account there. My secondary monitor has a dxnothing screen running 4 VideoFX. It's a 1920x1080 screen so each char has a 960x540 space using the whole screen. Each VideoFX shows the exact account always and they dont move positions or rotate, so it's a lot easier to watch. U know that top right is #2, bottom left #3, bottom right #4. Top left which is #1, I just place a movie or chat there since the main screen already shows the active which in 95% of the time is #1.

Besides this I have a few overlays on the main screen with VideoFX as well to show the mana pool from each char right beside the main char mana pool. Also 3 small minimaps from each char near the minimap of my main. With that and audio, it's fairly easy to loot.

Death Breaths are a pain now. Just do T7+ and u know for user each elite will drop a death breath. Or have a farming set for Death Breaths with Sage set and just take a full day just to do this and mass a huge amount so u dont loot them in weeks. What I usually do is just loot Death Breaths whenever there's a legendary. Every time I hear the sound, I stop and loot on each account. That or just use a macro on my mouse to spam left click like crazy and loot on the fly ... it will most likely pick some