Hard to say - even New Agey stuff evolves. (Not many followers of Reich pushing their copper-lined closets these days.)

Generally, background stuff is enough. There's no shortage of hard scientific evidence about yoga or meditation, for example. No need for heuristics there. Similarly there's some for float tanks. In fact, I'm hard pressed to think of any New Agey stuff where there isn't enough background to judge it on its own merits.