Or you could just have it all the time as a Dark Knight, and not be held back by the buff wearing out.
You don't know what I'm saying, do you.
If you get DK Aura from someone else, you not only get the +150 max stamina, but you also get +150 current stamina. As in you get free stamina. You can go from 0/160 stamina without Aura, gank someone's Aura, and be at 150/310.
DK Aura is actually much more beneficial to other people than it is the DK, unless the DK in question is a Spear Lann.
I've had moments on my hammer Fiona where everyone transed, and I was able to spin for almost all 2 minutes of my trans without any breaks because of the free 150 stamina I kept getting every 15 seconds.