Hi All,
Dad and I have been using Carbon booms for the past 4-5 seasons. Our sections were made By Composite Spars and Tubes (CST) in Sydney, (they make everything carbon, tillers/rudder cross bars etc) Dad worked with them to come up with a 50mm tube section that is doing an excellent job which we have never had any problems even in a few 30knt plus winds, will break alot more before break carbon.
Our outhaul system is pretty much the same as Peter Hallsworth decribed, the same as the A Class system with a loop on the mainsail clew and then 2:1 system internal in the boom, this works well.
If anyone wants any details on the section specs, Dad or myself will be happy to help you out.