In my experiance, not withstanding any documentation, ALL sand can be an impactation risk for such small animals. Calci sand is worse, as the leo will activly eat it to get the calcium, but all other sand is non digestable.
Of course, some may travel through the gut and get passed out, but some wont.
HOWEVER, The risk is not in the using of sand, but the chances of a leo eating it.
If you sit and watch a leopard eat, it is pretty good at filtering out bits of 'non-food' as they do in the wild, bits of chip or aspen that do get collected along with the crix are either left to fall out the side of the mouth, or are 'spat out'.
However, young geckos are so ravenous for food and move so fast, they often dont relise what it is they have collected, just like a human child !
For this reason, I would recomend that sand 'can' be used for leos over 6 months, but NOT for those under 6 months.
I wont go into which is best in this thread, but will say I use play sand when i use sand at all., and its normally only in the area the leo uses for its loo.