Yeah. That's the only thing that having a manifold would help as far as heat. Having the coupler/fitting directly attached to the compressor under the hood would get hotter than having it go through their manifold with the included metal braided lined. I've never had an issue in the NM desert heat, but I won't discount a manufacturers recommendation based on my single experience.When you say connector, are you referring to the air coupler/fitting to attach an air hose?
With all that said, there are a lot of ways around their $75 Manifold. It looks like event wits end sells a similar manifold for $20. I would guess that I'd spend similar or a tiny bit less making one myself.