comparison with other private file modules like assest

Could someone with more experience help me see the differences between private upload and asset ( http://drupal.org/project/asset )? It seems private upload only allows roles with permission to the node files are attached to to view the files, but with asset, you set the roles that have permission directly on the file? Well, any experience with both would be helpful. Thanks! I'm sure both are fine modules, I'm just trying to find the right one...