I went skinny on Troppo's advise, and find it heaps better.
As with alloy or carbon, I do freeride slalom with a 6.6 sail in rough ocean, and find the carbon a lot stiffer when overpowered or hit with gusts. I've been breaking alloy booms within a year, for years, as do a lot of guys. But it wont be long, and I'll break even on cost, the carbon has lasted double the time so far and feels better.

As with cycles, a mast is flexing non stop, and a good full carbon skinny will last for donks. A alloy boom is like a spoon, bend it back and forwards enough and it'll break.
Just my thoughts