Am I relying on SSS too much?

I think you're in the right ballpark. At 50mm I can usually get sharp shots at 1/10th or 1/20th shutter speed. Sometimes as slow as 1/4 or 1/8 if I'm lucky.

Of course, with moving subjects, that goes out the window. But I do find the IBIS to be worth 2-3 stops -- a big advantage.