Basically fixes the problems with SRTM, but you're still left with 30m resolution.
You can read more about ArcticDEM here: https://www.pgc.umn.edu/data/arcticdem/
Seems like EarthDEM is the same. So all the advantages and disadvantages that come with stereo photogrammetry. Very high resolution, but potential for inaccuracy and quite difficult to check. Probably they used SRTM or something similar to validate their models.
>IceSAT altimetry data points are used to improve the vertical accuracy of both the DEM strips and mosaic files. IceSAT data points are filtered to exclude points in areas of high relief and over hydrographic features. Additional filtering is applied to remove altimetry points collected outside the temporal window of the source imagery acquisition date.
An xyz translation is calculated for each strip and the offset is added to the metadata file. The individual DEM strips are not translated before distribution. Users can apply their own corrections to the strip if they do not agree with the one originally provided.
Where available, additional control information such as LiDAR or surveyed GPS points have been applied.