Isn't that a selling point of ARM? Would you prefer a passively cooled but only slightly slower laptop or a faster laptop with a noisy fan?

I don't think there can be a universally accepted answer to this, as there are so many different user priorities for laptops.

Having said that, I think the top requirement for most laptops is that "it's gotta run what I need it to run on day one".

For a huge amount of light users, ARM Macs are going to satisfy that requirement easily.

Once you move up the food chain to users with more complicated requirements, however, it's less of a slam dunk... for the moment.

This is like saying Qualcomm and Samsung should be able to make top tier desktop chips but the reality is that it doesn't translate so easily.

I guess its all trust that Apple can pull it off and there's no detailed rumors yet?

That's because neither does build even a top tier mobile ARM chip. Each of their best offerings is about half as fast as Apple's A12X/Z

Because with the A series they show that they know how to make a good CPU that fits into the thermal restrictions of the chassis.