It's interesting that they mention lines and line coverage so much and not statement coverage. I would think that statement coverage would be a much more effective measure of what should be mutated if the metric is available for the instrumenting tool being used, otherwise it's often just going to be testing which covered lines contain uncovered statements. In other words, it's doing the coverage tool's job.

In any case, it seems like it could be a useful tool if developers know how to use it. It seems like this is ideal for catching tests which fail to actually test statements despite covering them. Like the post below mentions, it will probably result in tests that just detect change if developers are not trained on the tool and testing strategies.