I can agree, but isn't it so that the meaning "by default" (without more context) of awesome is positive and is rather negative for ahurissant?
I mean: you cannot just translate an awesome movie by un film ahurissant (it would be: génial, formidable, terrible...).
On the other hand, if I hear il a eu une réaction ahurissante, without any more information, my first reaction would be that the speaker is not very pleased with the reaction of this person.