Poncho as ground sheet

Are they silnylon now? My GoLite weighs 10 oz, so maybe they changed the fabric. I would think it might allow moisture to seep in. Also sil is pretty slippery stuff and that might be even more frustrating. But a 7 oz piece of rain gear is fairly light. Might be better to use a polycro ground sheet for a 1 oz penalty. Could be used with the SpinnTwinn and the poncho in tarp mode. My original GG polycro has held up for a long time and I still use it at times (I bought several thinking they wouldn't).

The newer versions of the GoLite Poncho are 7oz http://www.golite.com/Poncho-Tarp-P885.aspx

The material is described there as 15 Denier Ripstop Nylon with Silicone/PU 1200mm Waterproof Fire Retardant Coating

Sounds like the Polycro is probably the way to go and avoid possible damage/puncture to the Poncho.

I'd go with polycryo groundsheet. Years ago we used to use our ponchos as groundsheets all the time; one day when it actually rained hard I was amazed to find that my poncho leaked like a sieve (and that was back in the day when they were urethane-coated tough stuff).

I am using my older 10oz Golite poncho as a ground sheet. My main goal is to destroy it so I can justify to my wife my dire neeeeed to get one of Zpacks cuben poncho/ groundsheets. Sadly, it is proving very effective and durable so far.