Well i've been debating on getting the hammerschmidt for months now and the time has come. Now i can't decide whether i want the FR or save the 120+ grams and use the AM. I am a light rider (150) and wasn't sure i needed the heavier bb spindle and thicker arms for, 'impact resistance.' Beyond what i can read online, has anyone used either model who can offer input and see a disadvantage to using the AM on downhill bike( session 88)?