Does it make sense to test responsive layout cross-device?

we are currently planning a relaunch of our web frontend into a new responsive design.

We currently use Selenium for functional tests and most probably will use Galen Framework (or write an own little framework based on Selenium) for layout tests.

There are points where we have differences in our opinions.

In this context of the relaunch cross device tests are only considered for layout tests.

But, based on my experience and bug findings, I think it does make more sense doing cross device functional tests instead of cross device layout tests.

I believe for most cases (most enough to ignore the little rest and their little effects), testing layout cross device is fruitless and unnecessary overhead, thus resizing the screen should be enough.

What are your experiences? Do you agree with my opinion or can you convince of yours?

Thanks in advance.