And so, when the save or die monster becomes apparent, you (and your character) will behave in such a way as to avoid having to make that saving throw in the first place -- which is exactly what i am talking about. it isn't quite "terror" but it looks enough like it to call it a duck.
But I would counter with: does my character know the creature, and if not, why would I be afraid of a save or die effect I do not know about? Player vs. Character knowledge...
OR
Surprise round, and I get hit with a save or die effect, and die.
OR
I've fought the creature before, and my character wasn't effected by the save or die mechanic, so why would he/she be afraid of it?
If the player decides that a character should be afraid of a creature, that's fine, but don't give me a power that kills my character with no other option. My characters are not walking encylopedias of monster knowledge. Even if I has the player know what the monster can do, I will play my character accordingly.
Also, I would rather have a series of chances of failing at something (like the 4E death saves system), which would give my party members a chance to help than have 1 shot, and if I fail, I die.
I also never liked the level draining mechanic either. I understand the concept of it, that the creatures are draining your life force from you, but when you are losing levels, they take experience points from the character, thereby making it effectively that the creatures are draining experience and not life from a character, unlike losing healing surges in 4E.
Don't think I'm saying "3.x sux, and 4E roolz". I'm not. I would rather play 4E, I like the system more than the 3.x system, but I don't think that the 4E system is perfect. I just like the fact that they did away with the Save vs. Die mechanic.