bryanlo
First Post
IMO, this is a side effect of the critical hit rules. You have to roll a natural 20 to score a crit. Getting a "spend a healing surge!" result on a death save is a very similar mechanic that triggers when you get a 20. Therefore, players draw the logical inference that a natural 20 is required even though the rules do not actually say so. If you'd asked me, I could not have stated with confidence that you didn't need a natural 20.
I think the game designers would have been best served to write it as requiring a natural 20 and then build in specific exceptions for feats that grant death save bonuses: "You get a +5 on death saves, and can spend a healing surge if this results in a roll of 20 or higher."
As things stand, they're screwed no matter what they do. If they fix the death save system to match the critical hit system, or remove the "healing surge on 20" rule altogether, they'll confuse players who've gotten used to the current system.
I think it's clear enough. In the online Compendium it says "20 or higher." and there is no mention of crit.