I also have a Giant (an NRS Composite 2) and I have upgraded to some carbon components since this is my first full suspension bike and I wanted it to be very light. Plus, my frame is carbon, so it looks great adding more carbon components. Although I considered the Easton EC90 handlebar, I felt more comfortable with the EC70 since it would most likely take more of a beating, I can still use bar ends (I bought the Control Tech Carbon Stubbys) and the weight difference between the 2 are probably not negligible. I had the same feeling for the seatpost, which is a Thomson and it is light and super strong. I have read some reviews on carbon posts that scared me. And, I went with the EA70 Stem which is aluminum, but only 135 grams and very strong!
Those are my thoughts. Good luck!