The product is not a DIY FMT, but serves a similar function (restore missing aggregate metabolic pathways).
Personally, from generation 1 of our product onwards I've felt considerably less stressed, more upbeat/happy, and haven't had diarrhea (I have IBS-D, so that's a huge one for me personally). Our pilot study has offered us preliminary confirmation of this, so we're paying for a 200 person placebo-controlled follow up study.
Early versions did have hiccups, but IMO gas is FAR preferable to diarrhea.
I don't personally think DIY is worth the risk, as there are a lot of things you'd absolutely need to screen for if you're considering that route (see http://www.medscape.com/viewarticle/776501_4 for a minimal list). I think you should also screen for mental disorders, stress disorders, mood disorders, etc. Basically anything known to be correlated with the microbiome at minimum.
Assuming you've screened for those things (which is to say basically a pro-level FMT), I think it's basically safe -- there are a lot of FMT procedures performed every year with minimal side effects.
#include disclaimer: obviously not medical advice, etc, etc