Wow. You must have really played it safe levelling up. I've had numerous moments where we strayed too close to another group, or a wandering elite or boss stumbled upon my in-progress massacre of his friends. Such a situation wouldn't really be much of a pulse-raiser with Doc out. With Kira? Different story. Often enough, when that boss comes around the corner, we're still halfway through the group we're working on and health is starting to dip already. No way to placate the dude and run away, so we charge into it, pop every "oh sh**" power in the stack and make judicious use of force stasis and other defensive powers. I've managed to pull out some pretty miraculous wins when Kira and I were both down to 25% or less health. Granted, I had to use Unity, Heroic Moment, etc, but those were still fun, survive-by-the-skin-of-my-teeth sort of moments. Best parts of the game.
I agree with whoever said it above (I can't be arsed to look), I use Kira for faster questing. Sure I spend a few moments in meditation between fights, but overall the fights go a LOT quicker and tend to be simpler. The longer a fight goes the more I have to concentrate on focus management, cycling the right powers through, etc. Much easier to let Kira join me and rip the hell out of things in the first pass through the powers on my bar. I will say this, though, working with Doc has taught me a little more about the class and how to manage cooldowns, since before I used him I didn't really have much need to learn it. This class, particularly with Kira fully kitted out, has ridiculous DPS.