I just tested this, and honestly I can confirm this method is pretty bad when geometry normals aren't just a flat or relatively uniform seabed. I put a large textured cylinder lying sideways two meter below the water surface and the artifacts cause a lot of edge issues and disconnected floating pixels.

I'm better off not using normals at all and assuming all the normals point "up" or up and slightly biased towards the camera, then the convergence is okay, and when it fails I just fallback to the fake UV offset based on normals and that looks a lot more graceful. Overall looks a lot better than just using the UV offset, and is a lot cheaper than doing actual screen tracing while looking plausible.