Are carbon-plated shoes worth it for a HM? I'm hoping to run it sub 1.40. I ran my first HM last year (1.46) with Nike Zegamas (I know, not road shoes). I now run with Cloudmonsters

Many factors including your running gate,  (they are more effective if you heel strike or mid foot strike - but do t change your gate because of this), the course etc. They are definitely faster, but over half marathon you also need them to be more efficient.  You’ll definitely be faster but hard to say by how much.

As you go beyond 1 hour the pace you can hold will start to be affected by the amount of energy you’re utilising and the regulation of your HR. If you have an efficient gate (use less energy/effort to move a certain speed) you will be able to keep your HR lower, body temp lower and maintain more energy.

Gotcha, great point. In what sense do they "need to be efficient"?