Hey Reader​

I spent weeks telling people to skip Opus 4.5.

"Too expensive."
"Sonnet does the job."
"GPT-5 is better anyway."

I was wrong.

The Setting That Changes Everything

Opus 4.5 without thinking mode is a Ferrari stuck in first gear.

Flip on "Thinking" (or "ultrathink" in Claude Code) and it becomes a different beast entirely.

Possibly the best coding model in the world right now.

Yes, including the brand new GPT-5-Codex-Max.

The Setup That's Been Crushing It

Here's my exact workflow in Cursor this week:

1. Opus 4.5 WITH thinking for planning (Plan Mode)
2. Opus 4.5 WITHOUT thinking for executing
3. Occasionally, GPT-5-High-Fast for code reviews

High-intelligence (but slower) for planning.

Lower-intelligence (but faster) for building it out.

The results have been consistently better than anything else I've tested.

"But Rob, It's So Expensive"

That's true, but a terrible mindset.

Opus 4.5 costs roughly 2.5x more than GPT-5.

Here's how I think about it:

If it saves me 5-10 hours of debugging per month, it pays for itself.

If you're billing clients or building products, the math isn't even close.

Remember that you charge for results and outcomes, not the work you put in.

Time > tokens.

Two Limitations Worth Knowing

First, if you use Claude Code in a terminal, it's a lot of fun.

You can run multiple agents, use skills, and it feels fast.

But... your project's code will turn into spaghetti as you lose track of your architecture.

Second, you can also run it inside of Cursor, which is fine.

But... that setup doesn't let you run multiple chats at the same time, which sucks.

I still struggle between these two workflows, and tend to fall back to the terminal myself.

The Bottom Line

Opus 4.5 with thinking enabled might be the best coding AI available right now.

The race is getting spicy. And if you're not testing these models yourself, you're falling behind.

Talk soon,

Rob

P.S. Learn my full AI building process start to finish in 30 days → Join 213+ builders inside​

P.P.S. Quick heads-up: I'm changing domains to rob@robinebers.com soon, so don't get spooked by a new email address 🤓