In my experience the dangers of mixing st john's wort with various substances are a bit exaggerated. I've taken it before in combination with cannabis, MDMA, ketamine, and possibly serotonergic psychedelics (not sure if I was still on it then or not). Not on one occasion have I felt any signs of toxicity. Can't tell you what it'd feel like with LSA as I haven't taken that in many years. LSA to me, from what I can remember, was pretty empathogenic though. Dunno if that was the SJW you felt or just the LSA by itself. It had a very earthy character to it, as all natural psychs do to me...
I've noticed that taking SJW for a prolonged period will increase my tolerance to cannabis and reduce the effects of xanax.