Using sling, daisy chain, rope vashe or something like Metolius PAS is all fine IMO to fix yourself to sport or trad anchors, so long as you obey SERENE; Secure (Solid), Equalised, Redundant, Effective, No Extension. The key is to ensure you don’t take a fall onto the anchorage system at all, whatever you use.
Besides this, I would like to see test results of falls onto a dynamic rope used to anchor in. If you use the rope at the belay to fix yourself to the anchors, would say a metre of dynamic rope have significantly more ability to absorb the shock load of a possible fall onto anchors than slings/daisy chain?
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