Wasn't there an incident two or three months ago where a climber fell above an anchor he was attached to with a spectra sling and pulled the anchor, resulting in his death? IIRC, it was either on Mont Blanc or the Grand Jorasses. From what I read, he had climbed about two feet above his anchor on a static sling. He slipped, fell four feet onto the anchor, which then ripped from the impact force, sending him to his death below?

Regardless, when anchoring directly to anchors with no dynamic rope in the system, if I'm in a situation where there is any chance of falling on the anchor, I would use a Purcell tied in 7 or 8 mm perlon. The perlon stretches a bit to absorb force, and if you really generate a huge amount of force, the prussic will slip to help dissipate it.