Everything he said is correct.
I'd also add that changing your adaptation by situation is required when you're doing hard stuff. It's not just Offensive all the time, unless you're ok with being dead some. That group's alpha strike too powerful? Just go in with Defensive and change after 3 seconds. All your good heals down and you're hurt? Go into Efficient until that changes.
It's a very clicky power set, which is going to eat into your dps clicks. That's sort of the reason Offensive has the big damage bonus. If you're doing stuff where you're just invincible in Offensive though, that's a lot of damage.