Puff has been on sand her whole life *from hatching till now*. She has never had any problems with pooping (she poops every other day as a matter of fact lol), it is sifted playground sand. Yoshi used to be on carpet but I found it to be VERY hard to clean (carpet holds ordours like mad). Yoshi seems to like her sand, she digs in it like crazy.
I never feed them off their sand, they eat all their salads off a plate, or bowl. When they get crickets I watch very carefully to make sure they arnt getting sand in their mouths while hunting.. I did buy some more repticarpet a while back, but I havent decided to put them on it yet.. Still debating. I am a member of a reptile forum and there are quite a few people who use sifted playground sand like me.