Dude, if that's anything like the old Sturmy-Archer planetary-gear driven hubs, it probably would work really well for quite a long time, then need a massive rebuild. My manager at the shop I used to work at knows how to rebuild those things, and if anyone ever came into the shop asking about getting one rebuilt, he told me to tell them he had no idea how to do it. Something about getting a bucket, opening the hub up, watching the complicated mess of grease and tiny pieces fall into the bucket, then spend a week putting it all back together. Yikes.
I wouldn't be surpised if this hub is bombproof, but I couldn't find anything on the site that said it would be sufficient for MTB use. Just wait till a good gear box bike comes out on the market. If you're a frame builder you're stoked, cuz with the disc brake mounts on one side of the hub you can drill six holes into a cog and bolt it to the hub. Bam, there you have another option to using a Nexus or Rolff hub on your next fantastic gearbox prototype.
I've worked on those hubs on bikes from 50 years ago or more. The only real weak part was the little pawl springs that would occasionally get too "limp", but other than that it's nearly impossible to break em. They've outlived most people in these forums.
Sturmey Archer hubs are the amazing, they'been around forever and they last like all the others have said. There are actually books out there, just on how to work on them. Complicated little things, it would be interesting to see if that one has as much resistance as the older ones.