The gift difference score is not dependent on syncing with your Steam account. Just go to http://www.steamgifts.com/group/f2hXw/goggift/users
find your user (you can search in the search field) and see you gift different score.
I don't seem to find myself. I thought I would still be in there since I'm on the steam group, but maybe not? I haven't been keeping up with the latest changes(meaning, the last year or more) so I could have been kicked out already.
Now I'm curious, I'm going to go check and sync my account.
Ah no, there I am. Maybe the user wouldn't show up if I was not in sync, maybe I search wrong. Whatever.
I'm at +6 it seems. That should keep me safe for a while.