I'd put it this way, but keep in mind, this is just my experience:
Salvia is like Datura in that you are not immediately able to integrate your perceptions, even becoming delerious (i.e. not able to decipher reality from hallucinations/delusions, not remembering that you're seeing/feeling shit bc you just did a drug), but, unlike datura, the trip is more memorable (many people black out and don't remember a thing on datura, despite the fact that they had, say, engaged in hours of conversation with someone who wasn't really there). I don't recommend datura.
Salvia, if compared to LSD (relative to the form of the acid, because different kinds are more potent), I would say is much stronger, but I have never taken more than 1 hit of acid (body weight and sensitivity). I do remember being in that 'delerious' state for a while, was certainly disconnected from my body, in that, I didn't feel 'myself' (hard to describe). I definitely hallucinated for about 5 min, thought I was in another time/plane of existence.
I think it'd be interesting to roll a couple of salvia/mj joints, drop some acid, and smoke the salvia joints soon as the acid kicks in. (but I'm not sure if salvia can be smoked in a j. anyone know?