Arena CEO @ml_angelopoulos reveals why the "cheapest" AI model can stop looking cheap once you measure cost per completed task instead of cost per token: "Our goal is always to get deeper and deeper in people's real work." "People are so fixated on cost per token. At Arena, we really believe that you need to be evaluating things on cost per task. On the Pareto frontier for agents, Claude's on the top, it's Sol, and the Gemini model is not quite Pareto frontier." "It's telling you not just…