Only advantage to aluminum, other then the obvious cost difference to manufacture, would be the material is more resistant to hits on the tubing. While carbon is designed to be strong in particular areas, the sides and strength of the tubing typically cannot resist a hit as well as metal tubes. Aluminum might suffer a dent, where carbon might see a hole punched. I actually know a guy I ride with had his (new) carbon Specialized take a stick into the down tube, made a hole. Either new frame time or sometimes a repair.
Very specific though as to the type of hit, damage resulting, etc.... some cases carbon might be better. You hear of aluminum wheels just folding from some hits where a carbon rim might bend and bounce back with good results.
Bigger question to me is can you get better wheels and components on an aluminum, where you would take lesser components on a carbon at a similar price point. When you consider that the aluminum frame can be built near the weight of carbon, means you might never notice a differences in ride quality, which in any event and for an HT would be as dependent on wheel design, tire size and air pressure in the tire.