I have 3 tangs in my 280g, a sailfin (Zebrasoma) who at the largest of the bunch is the undisputed king of the tank, and then two Acanthurus tangs, a lieutenant and a lavender. I have had all for a while and came forward from previous tanks. The aggression between the two Acanthurus at first was pretty nasty but subsided after 3-4 days.
They seem fine for the most part but even in the 280g there are times one or the other is scratched up. I have no plans to add any more tangs, at least none of the Zebrasoma or Acanthurus variety. Aggression between fish, even temporary, tends to stress me out and I'm learning that I'm happier when I avoid unnecessary stress.
Triggers are awesome!!! A pair of bluechin/bluejaw would be a lot of fun. They are in that genus of trigger that includes the bluechin, the sargassum, and the crosshatch and these are regarded as the most reef safe of the trigger family, as they are primarily planktivores.