I have used their 35 - 15 probiotic. I did a homemade test and its an OK and cost effective probiotic. Not as good as the high end stuff but I mix with a couple of these and a good one plus sacchromyeces.
Haven't used anything else. NSI is vitacost's generic brand. I think they had a problem once with a supplment - don't remember where I found - maybe consumerlab. I generally try to use USP or NSF verified supplements. However - there aren't too many of those. Then I look at if they are verified as having good manufacturing processes and how other supplements by that brand test in consumerlab tests. ALso try and get US manufactured supps. There is a class action in CA right now on lead in supplements. Its a significant problem since not FDA regulated.