I agree completely with billk. I usually sew very light weight rip-stop (making kites with kids), and for that an ordinary size 60 or 70 Universal is excellent.
The only problem you might encounter is the stuff slipping or sticking to the machine/foot . Which is does depends on the coating and the side of the fabric you are working on. I find that a roller foot* or Teflon** foot and slightly increased foot pressure helps. I also use as long a stitch as I can: fewer holes to seal and a reduced chance of the stitches ripping the fabric (and yes, along a seam with too small stitches, even rip-stop will rip!).
Teflon 'easy glide' feet:http://www.bredons.co.uk/bernina-sewing-machine-foot-no-52-zigzag-non-stick-foot_397.htmhttp://www.bredons.co.uk/husqvarna-sewing-machine-smooth-glide-non-stick-foot-h_292.htm
Other manufacturers do them, and you can buy generic ones, though I find the brand specific ones are usually better made.