No you are not, because ShS is a very nice mobility CD, BUT:
You can either have the one or the other, both is op. Sorry to be that hard to our class, but its a fact.
PvE wise, ShS and Prep are both viable choices, depending on the situation. 5man and heavy movement encounters, I take ShS over Prep every time. Otherwise, having a second vanish for FW or double my defensive CDs is simply great.
And the best thing is...I can take both of them regardless of my spec...yes, its sad we can't have both, but I won't miss that, as long as I can use them IN FREAKIN MUTILATE SPEC ;-)