My terribs will eat 5/8" crickets and they are very interested in adult crickets but they can't seem to take them down. They will literally stalk them all around the tank and harass the cricket constantly attacking it but can't seem to get them. So I just use 5/8". They will readily take even the largest wax worms. Recently they have gotten so bold they will attack the food from my hand before I even have time to drop it in the tank.
The Silverstonei I had at the Cincy Zoo were the largest darts I have ever had and were voracious feeders, I know they ate cock roaches which was payback since cock roaches ate their babies...morning geckos huh, like to see that, maybe in a Terribilis tank they would be mourning geckos.
I've seen vittatus take huge waxworms, almost as large as themselves. The one female would jump on the worm mouth open like a piledriver move and ram the worm into her mouth, pretty impressive for a small phyllo. It's been the most impressive gluttony I've seen with darts hands down.
I never tried huge bugs with my silverstonei but they ate a lot of small crickets.