The latest version of Warhammer has an interesting option, you can move your player down a track where they engage with more risk for a higher pay-off as the combat ensues or they can go the other way for less risk and a lower payoff. I really liked this bit of the game, as it let me (who likes lots of risk) and more cautious people get what we wanted at the same time. It's kind of like that Careful Strike power in 4e: I wouldn't bother with it but some people like more certainty for a lower payoff.
Removing the specific Warhammer rules, I'm fine with the concept that my character could engage in more or less risk than another PC. If you said to me "make 10 rolls and if you fail 5 you die, or just make one roll now" I would take the one now, but I wouldn't want to force anyone else to do the same.
In line with modular design, how about this for a mechanic that suits both ideas at the same time? If you are affected by a deadly spell, choose either to:
- Push through it: Make a easy roll and shrug off the effect or die; OR
- Shake it off: Take 10 ongoing and make a hard roll each round to stop the damage.
So you could have mathematically equivalent and similar rules for all characters, but make it totally optional to the player and the situation. (Assuming, of course, that you also balance for the chance that someone could remove the ongoing effect by another means.)
Man, I hope something like this is in 5e, even as an optional module, because I'm ready to roll to "Push through it" right now.