The more I play D&D - and I play every week almost without fail - the more I experiment with bits and pieces of it. My combats are quite well known amongst my players for featuring bizarre creatures from all editions of D&D despite the ruleset I'm using being a mishmash of Labyrinth Lord and AD&D (essentially, I use Labyrinth Lord as the base and expand with 2nd and 3rd edition spells). I even throw in a few I have made up myself.
What happens is that various pictures of creatures emerge from different editions. In general, these are in line with what you might expect. Most creatures from basic D&D have far fewer hitpoints and limited damage ranges compared to creatures from 4th edition, which make for good boss creatures and leaders. However, despite the apparent deadliness of the monsters on paper, a lot of enemies I field at the players from later editions seem to have had the lethality drained out of them. By this, I am of course referring to poison.
When poison is save or die, there is real drama at the table. A character may have 50 hitpoints (quite a lot for Labyrinth Lord) and yet, here is a single damage point and the potential for instant death. And it all hangs on a die roll... That creates major panic. Its nullified somewhat by the party cleric keeping neutralise poison memorised and having a raise dead and a resurrect scroll... but everybody seems to understand that these resources are finite and the danger is there. It just doesn't have the same effect when the poison simply is inflicting hitpoint damage per round, and nor does it when I play a game like the Bard's Tale.
So, I may upgrade every single poision wielding enemy to the save or die type. My group has generally very nice poison saving throws on their characters, do have some antivenoms on them and there is the cleric too. I normally give an hour, when someone is infected by lethal poison and collapses into unconsciousness, before they will finally die of it. In that hour, panic rises...