I've only ever used (decent quality) fake grass cut to size. I have spares as well so it's so easy to change over when cleaning out. My largest female thrashes her feed about on occasions pulling it all over the terrarium and I never have the worry of loose substrate sticking to the food and possibly causing any issues.
Fake grass works great for me, also use it for my leopard geckos and they quite happily sprawl themselves out over it.