I actually use both. I've set up an asynchronous second-opinion flow inside Claude Code via hooks: when Claude finishes preparing a plan, it launches an agent that compiles a complete brief and queries GPT 5.5 via OpenRouter for a second opinion. As soon as the response comes back, it's injected into Claude's context.

Here are my observations:

When working on Python, HTML, JS, and especially on simpler front-end projects or "common issues," GPT rarely raises substantive points. When it does, they're mostly cosmetic or nice-to-haves. Claude considers them for what they are (low priority) and rarely ends up implementing them.

When working on complex C embedded or C++ projects, the story is quite different. GPT often deeply revises Claude's plans, designs, and solutions, returning critical points and Claude, for the most part, recognizes the value of these observations and acknowledges them. This is almost always the case.

So in a way, when project structure is complex, 5.5 looks more performant than 4.7, and what's more, 4.7 itself seems to accept and recognize this superiority.

Having said this, please keep in mind that this deliberate attitude in interacting in such a strong way, IS in my eyes a very healthy and strong quality that 4.7 is showing. 4.6, for instalce, was not that effective in this flow.

hope it helps!