The toads got their bodies smashed because of their own mass pounding into the ground. Of course, the stronger the Shinra Tensei, the stronger the impact, up to a point it would smash Raikage's body as well. But Raikage's speed and reflexes make it difficult for Nagato to focus such a Shinra Tensei, limiting him to a defensive usage. So if Nagato reacts to Ei coming close, his Shinra Tensei will serve for defensive meanings, merely pushing him away from his distance.
Let's be serious here; This character will be way too fast for Nagato. It's not only Ei's maximum speed, but also Oonoki's technique which lightens his body and further increases his speed. Sasuke had the advantage of his Susanoo being a permanent defense, and more important, covering his Susanoo in the black flames, so he assumed that Ei would stop his attack, as he would sacrifice his own arm in the process of the attack. Nevertheless, Sasuke got stroke in the face.
Nagato may react and keep up with Ei alone, but never with one who is boosted by Oonoki's ability.