Felids lose a level upon reviving, so I guess they beat you to it, if I understand you correctly. Or we could say that great minds think alike!
Losing a level can be very icky depending on how it's implemented. If the game keeps track of what you gain at a level up, or if what you gain is predetermined, then it isn't an issue and removing a level is as easy as adding one. This is less true if removing a level means you suddenly can't hold all your gear and you need to spend 5 minutes reconfiguring your inventory, or if it means you need to, say, reorganize your passive abilities since you no longer have enough "ability points" to use them all (though I don't know of any games that have a system like this, outside of say Final Fantasy 9).
If your stat gains at level up are semi random, then level downs can benefit the player or hurt the player. Say you gained 1 strength, 1 dexterity, and 1 wisdom on reaching level 22. Then you are leveled down and you lose 1 wisdom. That's a great deal! Or you could have only gained 1 of something on level up and then lose 3 things on level down.
Even my negative experience idea can eat total shit depending on how experience is used in level gains. If the game only tracks experienced needed to next level up (and then either pulls the experience needed for the level up after that from a table or follows some kind of algorithm to determine experience needed after you reach that level) then you can apply negative experience all day with zero consequences.
But if the game tracks
total experience to determine when you level up, then you need to cap the amount of experience you can lose or else you'll lose a level and weird things could happen if that isn't what you intended to happen (and weird things will probably still happen). Even then that creates something that can be abused, because it means you can take risks when your experience is very low without losing much experience.
I can only endorse negative experience when used with a system where your game tracks only experience needed to the next level up.
You could penalize the player even further by tracking total experience acquired and total negative experience acquired, and then do stuff with that even though it isn't used for level gains. You could make certain quests time out once you reach a certain total experience and not have total experience take negative experience into account, punishing the player if he or she grinds too much or dies too often (an event ranking). You could increase the difficulty of some encounters once certain milestones in total experience are reached (sort of an encounter ranking, or a battle ranking).
You - or your player's god - could reward the player with gold or random useful stuff if the player manages to reach certain events with a very low total experience and little or no negative experience. I prefer that the player not be rewarded with permanent stat boosts or otherwise-unobtainable abilities or items, because such things bring out the completionist in me and I like my social life!