Insect (cricket) protein is already commercially available. I'd imagine they've tested the safety to some extent. People eat whole bugs and tarantulas all over the world.
In terms of sustainability, I don't buy the argument that beef/pork/chicken is unsustainable. Capitalism is inherently sustainable because as supply decreases, prices increases and it lowers demand. Sustainability issues come into play when there is a community property, like an ocean, lake or river, for which there is no disincentive to fish or hunt. Assuming these insects are farmed on private property, they would be equally sustainable.
Environmentally, I really have no idea. Some animals and land use permits are better or worse for the environment. Free range cattle, for instance, are great for the environment, but something like factory farmed pork, isn't. Don't know enough about insects.