X: Mike P's Grok 4.6 vs. Opus 5 on a Long-Data Fitness Report Task

Test task

The author gave the model complete Garmin and Apple Health data from 2019 to the present and asked it to generate a fitness report covering all types of exercise. The report was to focus on the author's cycling history, track long-term metrics and progress, and include charts, while allowing the model to decide the report's visual format.

The author had previously compared Grok 4.5 with Opus 5. After clearing the context, they ran Grok 4.6 again in Grok Build with exactly the same prompt.

Results

• Grok 4.6 chose to output an HTML report. Its formatting was clearly better than Grok 4.5's, with no obvious formatting errors in a single generation.

• Its data analysis was better than 4.5's and added some insights that 4.5 had overlooked, but it was still not as deep as Opus 5's.

• The author still ultimately preferred Opus 5 because it assembled a more complete story from the raw data, while also believing that the gap between Grok 4.6 and Opus 5 had narrowed substantially.

Value

This is a combined sample involving a genuinely long context, structured data, charts, and a visualization deliverable, making it closer to real knowledge work than a one-off code snippet. It also shows that formatting completeness and analytical depth need to be scored separately.