Hmm, I'd be interested in seeing Shadow get something like "Fade, for Shadow spec, now removes all poisons and bleed effects and makes you immune to them while active".
Really we should be immune to them all the time, we're not corporeal - we don't have blood, we can't bleed without blood, you can't put poisons into our blood when we don't have blood. It becomes really bizarre when you think about Fade - with Fade, we are not even a Shadow, we are the remmant of a shadow: how does that bleed?!
The alternative way to do it would be something like "For Shadow: While Fade is active the priest gains 30% dodge" - which also makes sense, as anyone who has attempted to deal damage to a shadow by hitting it with a sword will attest. I think people are less likely to cry about it if they lose their bleed/poison effects though, than if they suddenly see their abilities miss.
Loss of Void Shift will hurt shadow directly, but the real thing it will hurt is our comp synergy / utility.