Just curious what other bowyers are using for carbon backing. I've heard that some carbon isn't good for the belly or compression side. Thinking about using Gordon carbon sanded one side for the back with clear glass belly.
Also, if anyone has experience with Gordon carbon, how does stiffness/thickness compare with clear Bo-Tuff, say .040 glass versus .030 carbon.
Any info would be appreciated.

Try this at the bowyers bench page and you will get a little more exposure for your question.

Ridgerunner.  Check out this past post. It has some great points to consider:

http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=000354

I talked to Bingham once and he told me one layer of carbon backing (under glass on the back) will add 5 lbs of draw weight (compared to the same thickness of lamination of non-carbon).  Therefore if you build a limb typically with a thickness of .300 and that produces a 50 # bow, a .300 limb with one strip of carbon in the back would produce a 55# bow.  

Good luck