Yes, max effort is what the displayed-by-default score on the index is measured by. At xhigh, Opus 5.5 outputs 100M tokens, but remains only 1 point ahead of K3.1 rather than 5. And Sonnet at xhigh outputs 110M tokens and trails K3.1 by 3 points rather than leading by 3, at the same price point per mtok.

Opus 5.5 high trails K3.1 by 1 point, but outputs only 53M tokens, so it indeed comes out cheaper per-task. I think it's still remarkable that this is effectively an open model that matches the frontier for the first time in a long time, pretty much since DeepSeek R1.