Assassin/Ninja Help Air Assassin

I'm thinking of using this build when I reach the right level, and I'm not sure whether or not I should replace the Booster Plate with The Courier's Cape.

Here are the stats of The Courier's Cape:

Spoiler

Overall the stats are better, but I'm not sure. Should I replace it?

 

if you want.. test it out first (if you have lots of soul points) and if it doesn't work you have your answer
i have the same problem i lots of things but they turn me into a death trap (not good)