Good if you can develop a facility to upload PDF full-texts direct from the source like the way EndNote and Mendeley do, Or
Good if you can develop a facility to upload references from EndNote/Mendeley along with the PDF full-texts when it is available with the citation.
Import PDF full-texts directly from database, such as Web of Science, and also export these PDFs for Mendeley, Endnote, or others. That helps with large reviews. The user do not need to download all PDFs for localdisk.