I'm aware... but, more often than not, I prioritized DA-SE rather than DA-C&S because I'm just paranoid about mitigation.
I'm still far more accustomed to Pld tanking, so my biggest concern when switching over to Drk was ensuring that I was mitigating dmg effectively. For one, I'm not as accustomed to the CD's of Drk, and, whereas it was relatively simple to theorycraft which CD's work well together, I'm still not 100% comfortable with them in combat. I've been assured by my FC healer that I'm being overly paranoid, and that I tend to make healing dungeons "boring" by mitigating too much, but I can't help but feel a little squishier on Drk compared to my Pld... and, to be frank, I've seen enough selfish Dps-oriented tanks when leveling my Whm and Drg to know that I didn't want to be "that guy," so I have a bad habit of overcompensating by using as many Self-healing opportunities as possible (a habit I picked up from War).
You're definitely right about the most efficient uses for DA's though, and your starter rotation is solid. Given that I am starting to get more comfortable with Drk tanking, and I usually have more than enough MP to spare, its time I start taking my Drk out of the safety box and pushing its limits. Your responses have given me quite a few ideas for how to go about it. I'm still not 100% comfortable with my hotbar set up, but I'll definitely be giving this a try.