I'm a Clydesdale and I run Maxm carbon bars on both of my bikes. The thing I like about them is the aramid (read Kevlar) net structure that's bonded to the inside of the bar. Supposedly this adds strength to the bar. I don't know if this is true or not, but it makes me more comfortable as does the lifetime warranty they have for the bar. They rate the things for DH use so I'm pretty confident using them on XC trails.
I still have an Aluminum bar for each of them, but that's more out of being a bike parts packrat than any real paranoia about the part