@vlogic The clients I've worked with that are primarily concerned with mobile are few. I occasionally still have to educate clients on the importance of a responsive design and having a site that looks good on mobile However, the clients that have been concerned primarily with mobile already had existing sites that needed redesigned.
As far as how I approached the projects, I simply worked backwards from the mobile idea. Instead of sketching down, I sketched up and used basically the same content – hiding a few pieces of content and images on mobile.
Several years ago, I designed...for a client "alternate" layouts for desktop, tablet, and phones using Adobe Muse. One issue that came up was my client, had her clients telling her the mobile site made them wonder if they were on the correct site. Although the mobile site was fast, had all the same branding (prominently displayed Re/Max logo and Agent Name) and a link to the full site, a handful of her clients mentioned it. From there I started watching how more "alternate" or highly condensed responsive sites converted users compared to responsive sites with full content or limited reductions. From my experience the responsive sites preformed much better so I've stayed with basically just scaling down or up, depending.
Your idea for pushing beyond 992 I'll have to try seems like a good idea. The Wordpress frameworks I've been using allow that to be customized but I found I was still using around 960. Getting off target now but for all the larger screen sizes, I'd love to find a study if people view the web at full screen size or only use a portion. I've found a couple threads/articles on stackexchange but nothing conclusive.