Trying to compare survivability between DRK and PLD

[LilimoLimomo]

I like doing older content both solo and as a duo alongside a DPS (generally BRD) friend. In my heart I think I want to play DRK, but I feel like if I play PLD both myself and my friend will have better luck surviving in challenging fights. My problem is I'm not sure whether that's true, as I could be overestimating the impact of things like PLD's healing vs DRK's mitigatio. And if PLD actually is better at surviving, I'm wondering how meaningful the difference actually is.

So I tried to crunch the numbers and quickly became overwhelmed by trying to do math that incorporated not just healing ability but also things like mitigation, mana management, and limited GCD's to do it all in. I'm guessing that someone in the community has probably crunched all this before or at least has a better understanding, so I thought I'd ask if someone could point me in the right direction.

So if I want to solo/duo Extremes, Raids, and Savages without a Healer, how much if any will PLD be better at helping myself and my group survive relative to DRK*?

*Those are the only 2 classes I'm interested in, thanks!