I am glad you said, "Sturdier" than a fiberglass one and not "better". There is almost no way to use the words "steel tub" and "better" in the same sentence. A properly, or even improperly, installed tub should not leak at the surround joint because the lip in back would catch the water and not allow it to get onto the floor. Therefore, there was a "real" problem with the installation, but what it was we cannot tell without seeing the actual site. Almost anything is better than a steel tub, but a fiberglass one is not a great deal better in the long run.