12/21/12 - The Italian website Planet Mountain recently organized a very interesting test of the hardware commonly used for convenience lower-offs at anchors, as well as convenience quickdraws left on routes (perma-draws). The resulting story, by Emanuele Pellizzari, is particularly damning of hardware-store varieties of carabiners, which really ought to be labeled with the tourist word "snap links." The testing showed that, in Pellizzari's words, "Every 'hardware' carabiner sucks, to say the least…. Every 'climbing' carabiner, even the oldest, most used and worn, is better than the best new 'hardware' carabiner."
The hardware used on anchors varies widely, though it does seem that the majority of American sport climbs are equipped with gear specifically made for climbing. The Planet Mountain report did not examine bolts, chains, and other components of the anchor system, but other tests have shown these to be plenty strong. The danger comes when substandard lower-off carabiners are used. Although, as Pellizzari writes, "The loads generated are unlikely to be so high as to break these carabiners.... when top-roping it is best to add your own carabiner." Of course it's always best to top-rope off quickdraws, rather than the chains or lower-offs at an anchor, to prevent excess wear on the anchor.
The Planet Mountain testing also examines the relative strength of each component in fixed quickdraws. Bottom line: A climbing carabiner is the strongest, followed by a "maillon rapide" (quick-link), followed by the nylon quickdraw itself, which is much weaker than the metal components.
Pellizzari also urges climbers to be aware that hardware stamped CE might not necessarily meet the Conformité Européenne (European Conformity) standards for climbing gear. Instead, it might mean "China Export," with no guarantees of safety standards. You can read more about these labels and the testing at the Planet Mountain report.