ImpactStory is another very good tool to measure researcher impact but there is a fundamental difference between ImpactStory and Altmetric:
Altmetric is research product based, i.e. it gives you the number of citations of a given resource (paper, dataset, presentation, etc.) in blog articles, social networks' posts, tweets, etc.
Impactstory is researcher based. It provides the "degree of openness" of a researcher, as a function of several parameters, analysing up to the 100 most recent works linked to her ORCID profile.
So, if you steadily publish your scientific products on OARs and link them to your ORCID profile, your "openness" degree in ImpactStory will of course increase but one can't link any of the ImpactStory parameters to a specific resource on the OAR, as one can instead do with the Altmetric "donut".