Here: http://www.restoreplus.net/files/Journal%20of%20Applied%20Microbiology%202006... is a link to an article published recently in a respected scientific journal, showing the results of a double-blind placebo controlled trial into BLIS K12 use. It is clearly shown to improve halitosis in most (though, admitedly, not all) cases.
It's obvious that you should give it a go. If it works for you, great, you have your solution. If not, then keep trying. You can never find out if something works for you if you don't try it out yourself - there is too much individual variation in physiology to rely too much on others opinions. Also there are more loud voices here shouting this or that product is "rubbish" (mainly the voices of commercial competitors), than will ever be heard over the relatively fewer rational viewpoints.