I've been using Stans NoTubes for @ 1 1/2 years now. So far I've discovered lodged in my tires- with no noticeable pressure drop- a small 20 ga. brad, a staple (the large industrial type not the small office one), and 2 I'm guessing goathead thorns (in the same tube). I'm sure all would've resulted in roadside tube changes. I swapped tubes upon their discoveries. My wife's bike has both tubes that have lasted over a year since application and sealant is still good. I don't think it will work for larger punctures but for what I hoped for it's worked out well.
Hope this helps.
West