I've been on the SCD (which turned into a low-carb, grain-free diet with plenty of Gottschall yogurt) for 5 years. I have no symptoms, unless I screw up and eat the wrong thing. I can go months without so much as a twinge.
But, working with patients like I do, I got concerned what would happen if I came down with C. diff. So, while my half-sister was visiting, I asked that she give me a sample so I could freeze it in the event I came down with C. diff. She and I share a mother, so whatever inoculum she received at birth has done well by her as neither she nor her kids have any signs of digestive disorders- although I kind of worry about my niece.
Anyway- by the time I got the sample, I found out my information was wrong, and freezing would almost certainly decimate whatever live flora would be in there; long cold storage would be even worse. So- I thought, what the heck; I might never get this chance again. I prepared the sample in a HEPA-filtered workspace using sterile tools and aseptic centrifuge tubes. I didn't use a blender; I used a vortexer to homogenize the samples- there is probably no real difference between the two. The sample was prepared in sterile normal saline, and put where the sun don't shine using a cleaned enema bottle. I did the best I could to invert myself for ~5 minutes after inoculation. Due to my low-carb diet, I did not excrete for about 36-48 hours afterward.
There were no specific changes. However, I did a "challenge" consisting of turmeric in water; turmeric has always been a weak spot for me. Before I got sick- no problem. After my diagnosis, the tiniest trace of turmeric would set me into a series of hiccups that would last for half an hour. I had insufficient time to test whether this was still the case immediately before inoculation.
However, *after* inoculation, I found I could tolerate multi-milligram doses of turmeric with absolutely no problems. I cannot positively attribute this to the "transplant," as I have serious doubts as to how flora in the lower colon (i.e., the inoculum) affect what's going on in the small intestine (i.e., the furthest any turmeric could possibly have gotten in the time it takes for hiccups to develop).
OTOH, the smell of my feces changed; there definitely was a change in micobiota going on. Now, several months later, the smell is back to what it used to be- most of the time. There are presumably some permanent changes in terms of diversity.
It is extremely important to note that once you lose flora, you're probably not getting it back. Whatever it is you're born with- perhaps 800 different species- is gradually winnowed away, a function of antibiotics, the lack of lactic acid fermented foods in the diet, the relatively clean water and food we consume these days, and so forth. You don't get these back, and when you have children (usually in a nice, clean hospital) this changes even further.
This may be one explanation as to why the incidence of these disorders continues to climb: antibiotic administration, and cumulative loss of diversity as a function of environmental factors.
Be good to your gut flora. Successive generations will thank you.