I have an Atlantis with the Rivendell/Nitto front rack. When I went to install that it was obvious why there are no midfork braze-ons - it wouldn't have intersected the mounting points in the rack. I used the clamps that came with the rack and they work great and it is incredibly stable. I haven't toured with it yet but I have done a bunch of riding with fully loaded front panniers on it - no issues at all.
BTW if you get your Atlantis custom painted like I did (and now Rivendell is getting half the frames unpainted and you can get a custom paint job for only US$100 more) you can arrange to have braze ons added. I personally would only do this if you intend to use a front rack that doesn't connect at the top, like the Tubus racks.