Couch is 'agnostic' about what type of template you fit it into and does not change your design at all.
If your original template is responsive, the couchified version will also be responsive. The original Aurelias template was not responsive and so the final site is also not responsive.
that's the main reason I'm looking for a new cms.
As I tried to explain in the last point, responsiveness has nothing to do with the CMS (I'm speaking for Couch here). It is your static HTML design that has to be responsive.
Has anyone experience or an example of a responsive template for couchcms?
I'll leave that to members of our community to reply. I can only say that almost all the sites that I see getting built with Couch nowadays are responsive.
Technically speaking, everything that the Aurelius tutorial mentions applies exactly the same for a responsive design too.
Hope that answers your query.