I know a 530ish guy (high robustness) who is an SL7/9. Getting to SL7 at that Fargo is fairly common in some areas but I'm struggling to see how he's an established SL9. I always thought that was more the realm of people who are approaching or just over 600.
The 7/9 in our area was a Fargo 600-ish (now a Fargo 627 but he stopped playing APA a few sessions ago)
We also had a Fargo 540 7/8.