I'd prefer to have a carbon steerer as it would absorb a crash better than an alu steerer, and thus reduced the chance of the frame getting damaged.
it's all theory of course.
You might be wrong for at least two different reasons. First, a carbon steerer is usually both stiffer and stronger than an aluminium one, and second that a monocoque carbon fork doesn't have the weak joins at the fork crown which are usually the first thing to go when you crash a hybrid fork.
You might be wrong for at least two different reasons. First, a carbon steerer is usually both stiffer and stronger than an aluminium one, and second that a monocoque carbon fork doesn't have the weak joins at the fork crown which are usually the first thing to go when you crash a hybrid fork.