Doug, your answer to the question is "you know them when you see them"? I don't and I know, or have known, a LOT of meditators.
Next question: What are "well cultivated serious practicing silent meditators"? Geezer asks: And what, exactly are "serious meditators"? Dear Geez, It seems like with other things you know serious meditators when you see [sit with] them. SRF/Yogananda meditators it seems are well cultivated as serious practicing silent meditators. They are gathering for their annual 'convocation' this month in the LA area. They gather 5,000 or so meditators for their group meditations during convocation. In Fairfield we will have a few hundreds meditating together in the Domes. -JaiGuruYou