You know what this forum needs? A mobile version! If you're on the go, replying to posts, or making threads is hard to do; mobile devices aren't really the best at using internet forums, so if there was an app version of the GMC, that'd be awesome!
In web development a good responsive design is supposed to provide a good user experience to any device. The original idea of the web was that you'd request a resource from a server, it would hand it to you, and it was up to your device to render what was served to it.
Having separate versions of a site for mobile devices and desktop devices is not desirable, if that means developers have to create and maintain both. It is fine if they can fulfill the vision of the web by serving content in such a way that mobile devices handled it well, that's the best solution.
Defining "mobile experience" is vague anyway -- it means "small screen" as well as "limited bandwidth" and "screen keyboard" but many mobile devices these days have desktop resolution and pretty decent bandwidth. Depending on the mobile device, you might have a great, desktop-like experience, or you may have some constraints.
All that said, I do use some other forums which integrate with Tapatalk, and I prefer using Tapatalk-enabled forums with the Tapatalk app rather than through a web browser on my smartphone. I was hoping the new forums would support Tapatalk, but it doesn't. Reading the xenforo forums, there seem to be a lot of people who don't like Tapatalk for various reasons, it certainly doesn't seem to have unanimous endorsement from xenforo admins. So I'm not expecting this to change.