Diversity does seem to be a good thing, but that said, some of the reported properties of this particular strain seem especially interesting.
I think taking a single strain is not something you'd want to do long term, I'd assume it's better just as a short course to try and improve your gut bacteria balance, if you're having problems or have just had antibiotics. With a good balanced diet (prebiotic fibre etc.) I don't think people should really need to constantly be taking probiotic tablets, but kefir and yoghurt seem good generally.
I think taking a single strain is not something you'd want to do long term, I'd assume it's better just as a short course to try and improve your gut bacteria balance, if you're having problems or have just had antibiotics. With a good balanced diet (prebiotic fibre etc.) I don't think people should really need to constantly be taking probiotic tablets, but kefir and yoghurt seem good generally.