Ya they arent as good as the worm because they dont eat or anything once they are a moth but one or two are good treats and some chameleons can really like the moth.
Them oths do have pretty good nutrition as the larva spend their whole lives eating in order to turn into adults with enough fat reserves to carry out their mission. Also the internal organs and sperm and egg cells also add nutrional value.
After my moths have been used up for breeding or if I have any extra, especially females loaded with eggs, I feed them off. My chams go nuts for the slikmoths. The flapping wings draws the attention from every panther cham in my basement when the moths start emerging. Just make sure you wait until after the moths spit out the nasty brownish liquid they spray out after hatching. One time my cham shot a moth, the brown stuff spray and got all in his mouth while he was chewing and he immediately spit out the moth. After that he wouldn't eat them for a good month. So I'd say after they emerge give them an hour or two just to let them get out their guck. I do not know the nutritional value of them but I imagine that feeding silkmoths once in awhile can hurt, they can't be any fattier than superworms, thats for sure.
they have negligable nutritional value, having used up most of their reserves morphing from larva to pupae to moth. Especially if you let the moths breed and lay eggs before feeding off. But chameleons enjoy them and they certain do no harm. I always feed off the moths once I've got as many eggs as I want.