Nightfall is kinda hard to monitor on all chars at once. And when it procs, it will seldom proc on all chars at once, and therefor you will most likly just waste a global cooldown on all the other chars when you're mashing the button to get it off.

One reason I went deep into affliction instead of Soul Link is to get instant fear. When you cast sequence this, you have pretty good defence without a pet. This means that I can most of the time use demonic sacrifice for 15% extra shadowdamage wich is quite nice with this many dots

I also use a slightly different spec on each lock to maximize the utility I get from talents. One lock are specced with Shadow Embrace to reduce physical damage, one is specced Malediction for CoS, One are specced CoEx for slowing. Everyone exept the one using CoS have imp. CoA. As for health stones, I also have 3 different ranks. Quite nice to summon all soul wells before a fight starts