It's existed since the 1950's, has a 90+ % cure rate for one thing and if I had a clean sample, I'd try it. If you want to read more it's called Faecal Microbiota Transplant.
Additionally, on the 'what works for one doesn't necessarily work for others' bent. They used healthy donors as universal donors and still had the same 90+% cure rate. There is even an at home version doctors use in Canada.
We're all humans, what harms one of us will likely harm the others. As for the toxins you're trying to get rid of, you pass them out same as always. I see no reason a working cure can't work for everyone. Statistically, there will probably be some failure rate, but that doesn't mean it's necessary.