Comment by mike_hearn

I recently ported a personal coding agent from GPT-5 by adding Grok 4 Fast Reasoning. This was quite tricky. It wasn't just a matter of switching a model URL. Grok 4 Fast is vastly faster, but some things GPT-5 can do well Grok struggled with, aspects of the prompting style confused it too. I had to rework some tools and stuff.

It wasn't a huge lift, but there is some moat. And the results were worse than for GPT-5 which I suppose is not a surprise, it was always unlikely GPT-5 was wasting all those flops.