Handle bar bags for commuting

I have currently been riding a cross check with rear rack and trunk bag for a few things, extra undershirt and socks for ride home, wallet, phone, 2nd spare tube, wallet, so not too much stuff, but thinking about trying a handle bar bag once I get my new Gunnar Hyper X built up at the end of the month.  
     Also wondering if it's alright to use a handle bar bag with a  carbon road bar, just picked up a good deal on a 3t carbon bar that I was planning on putting on the new bike, but could also use the light older FSA energy bar that is alloy and put the carbon bar on my road bike instead if it's better to use the alloy bar with a handlebar bag.  I think a reasonable size handle bar bag will effect handling and weight distribution better, not be as heavy, and keep less weight over the rear tire.  I looked up the Oltreib handle bar bag that looks nice, but I guess they say you shouldn't use their handlebar clamp system on a carbon bar, but I know there are other handle bar bags that could probably work.

Thanks for any input.
Adam
Also if you have any recommendations for a nice set of metal fenders that you like.