Bing is now showing 'Mobile-friendly' label in their SERP's. I just found one of my site labelled in its SERP's this morning.
I think there are some complications regarding this as considering one of my site. Most of the indexed pages are non-labelled. And some of the pages which are non-labelled are showing good results then my competitors labelled pages.
Yeah, its true about the complications. I am also seeing many unusual labeling for pages.