Most high-end metals have very similar specific stiffnesses and specific weights. Steel, Ti, AL, Mag all fall into this category. Being much less dense in an absolute sense means that you are able to theoretically build a mag bike with very big, thin walled tubes to reduce weight. At some point you start to loose practical fabrication ability. At that point, Carbon again becomes a very good alternative. The older Dogma was a good example. Interesting bike, but the carbon version is lighter. I really can't comment on the ride characteristics.