still the same, if you want to backup entire home directory with a group, I feel quite troublesome, and it will bring your more trouble. Example like you need to force user write as group backup, all files/folder need to save as 660, need to overwrite existing permission and etc. Since you use the ssh, I think using root user is better than others.
However, for myself I'll mount it as local folder, so future it won't keeping send the username/password across the network(And I prefer rsync -ruv --delete).
Somebody have better ideals?