I take SP myself and still wouldn't say it compares to finasteride - dosages and quality of dosages vary too much for it to be anything other than something to work with yourself til you see results (or not, as the case may be). The studies aren't great science but then the studies for nizoral aren't great either! I think the theory of having an effect on DHT/5ar is pretty sound nonetheless ...people are taking green tea for less.
I like it cos I can buy it in the local health shop, I haven't loss much more hair on it and I dont get sides from it.