I recently use Import-PWDocuments to import huge folders (275000 files, about 700 Gb)
It worked quite well but i had 3 different issues,
#Needs 32bit verion of powershell
#This needs the PWPS_DAB module which is installed on the PWZ server. Also, please update the source code in TFS.
Set-ExecutionPolicy -ExecutionPolicy Unrestricted;
Import-Module -Name pwps_dab;