It might be a good fit for E6. Critical hits could still reduce people to 0 Wound Points but it wouldn't be as common, at least for characters who give a damn about their Constitution.
The thing I don't like about it actually is that people can get beaten to a pulp over and over again but as long as they make the save to avoid death [DC 15 Fortitude to avoid the Dying condition], they hover at 0 Wound Points. I think that's just ridiculous. If someone is at 0 Wound Points, I shouldn't have to nuke their save in order to force them to become Dying so that I can then hit them again with a Coup de Grace to force a saving throw at a much higher save DC.
The other thing that bothers me is the stunning effect of wound damage. If you land a critical hit, you also have a good chance to stunning for 1d4 rounds, which is a huge boon (save DC determined by damage).
Personally, I'd play it without stunning (someone who takes wound damage is already Fatigued, they don't need more punishment for getting hit) and rule that, once at 0 Wound Points, you die when your Wound Points reach negative half of your maximum Wound Points or negative 10, whichever is the lower number (the more negative number). This gives a bit of a buffer without the annoying issue of people never dying because they can make a DC 15 Fortitude save.
But I still wouldn't play it in a regular campaign. I really would be tempted to try it for E6.