I recently got a chance to look at the Six Moon Designs cuben Haven. The inner tent from a Coleman, Peak 1, Cobra fits nicely under it. A few minor modifications would make it work.

This is probably a match-up that very few would be interested in. The buyer of the 10 ounce, $400, SMD cuben tarp is probably looking for something different than the owner of a $69, Cobra with a 1.5 lb inner tent. But who knows?

The Haven/Cobra combo would weigh a little over 2 lbs for the tent+fly (excluding poles, stakes, etc.).

While it is a nice coincidence of footprint, I think the there are other inner mesh tents that would be easily adaptable to the cuben haven. Seems kind of like putting a governor on a Maserati or something.

I don't think there will be too many people doing this. The Haven net tent is considerable lighter that the Cobra inner tent and has substantially more space than the Cobra. I have both and the Haven net tent is definitely superior, plus it is designed spectifically for the Haven tarp.