They patented THEIR version of Threelac by tweaking the ingredients a little, so that they could rename it (Symbion) and make and take ALL the profits, instead of getting a commission like others who sell Threelac.
I would suggest researching probiotic strains before purchasing something as pricey as VSL#3 to get something that will help you.
In other words, do you have high histamine levels (lots of allergies or food intolerances )? Then you want to take a probiotic that reduces histamine (like b. longum).
But if histamine is not a problem, and you're looking to address some other problem, then you could research which strains will help that issue.