I have problems with my logo on mobile too. I sort of fixed it for now, but good to hear you are working on a fix.
Further problems after updating to 6.0:
– product title is bigger then normal (on product detail page)
– category titles are suddenly very large
– Shopping cart icon in header is different (both on mobile and desktop)
– filter button on category page is aligned to left (should be right)
– text in ajax shopping cart (drawer) is aligned in a wrong way
I have quite some custom CSS, which seem to be still working fine. But should I replace it in the future?