A few years ago, I purchased one of Six Moon Design's early tents (the Europa I) with a 70D floor and found it to be unacceptably slippery. On even the slightest slope, I found myself quickly sliding to the downhill side of the shelter. I tried sanding the surface, but it didn't help.
In frustration, I cut the floor out and replaced it with a lightweight, removable piece of polytarp held in place with velcro patches (works just fine). If I known then what I know now, however, I would have just coated the floor as described in the article.
I don't know if SMD is still using the same 70D silnylon, but since all the silnylon samples I've used in my various projects (all 30D, but from 6 or 7 sources) over the years were all very slippery, I'd guess it remains an issue.
I also can't really say if the 70D floor is more or less waterproof than the 30D floor (maybe Ron Moak can advise), nor can I say with certainty that the treatment would bond well with either (but it probably will with quality silnylon). BTW, in that regard, I think it's always a good idea to test a small patch of the fabric in question before treating an entire floor or canopy.
If it were my decision, I'd probably go with the 30D floor and treat it if too slippery (probably will be). The treatment with improve abrasion resistance, but if you plop your shelter down on something sharp enough, either the 30D or 70D will probably end up punctured. Small holes, even if they occur, however, are usually not a much of a problem and can be easily repaired if they bother you.
Having said that, I am a fan of lightweight ground cloths like a piece of soft kite Tyvek (#1443R) that would probably weigh about 3 oz for the Lunar Duo or maybe a polycro ground cloth from Gossamer Gear that would weigh about 1.5oz (though the stuff is a bit noisy for my taste).
Hope this helps...
Last edited by Jim Wood
on Mon Jul 28, 2008 9:07 am, edited 1 time in total.