Why not just get a more conventional helmet that has good air flow? There are plenty of them at all price levels that have excellent airflow and five stars from the Virginia Institute that test the helmets to see how well they protect.

I shied away from Wavecell because it just looked like it'd be hot. I have no idea what Koroyd is, but it sounds about the same as Wavecell. I'm sure they protect well, but when conventional helmets protect just as well, why not just get what looks like it will flow air through it?