Several people have commented about this probiotic available at http://www.gomegaspore.com/ and I am in correspondence with them to get more information.
My usual criteria is PubMed studies on the actual probiotic (by brand) or the strains in the probiotics. With reports of herx and the mixture of species (and some potential characteristics), I thought that should do a preliminary review simply because it is easily available in the US (and the last two cited require a European facilitator to obtain).
Pure Bacillus Mixture
First, in terms of lactic acidosis, there are no major lactic acid producing species (i.e. no lactobacillus). I received an email from the manufactorer stating that it contained
- Bacillus Indicus, HU36
- Bacillus Subtilis, HU58
- Bacillus Clausii (no strain specified)
- Bacillus Coagulans (no strain specified)
- Bacillus Licheniformis (no strain specified)
Two of the above (no strain specified) are known to be high histamine producers  and thus if you are in (or close to) the subset of CFS patients with histamine issues, this should be a DO NOT USE.
There are actually many manufacturers who have licensed some of these(HU36,HU58) from from Royal Holloway London University
- http://nusciencetrading.com/probiotics/ has HU36 & HU58
- http://thriveprobiotic.com/what-exactly-is-bacillus/ – “Just Thrive” has 4 of the above 5… London University
- As well as in bulk from Alibaba
Bacillus Indicus HU36
- A pigmented marine bacteria 
- “carotenoids from Bacillus indicus HU36 and Bacillus firmus GB1 were found to be interesting antioxidants to fight postprandial oxidative stress in the stomach.”
- “suggests that the two pigmented Bacilli are adapted to the intestinal environment and are suited to grow in and colonize the human gut.” 
- No Wikipedia or MicrobeWiki page on family
Bacillus Subtilis, HU58
- “B. subtilis examined here were HU58, a human isolate…Compared to a domesticated laboratory strain of B. subtilis both isolates carried traits that could prove advantageous in the human gastro-intestinal tract. This included full resistance to gastric fluids, rapid sporulation and the formation of robust biofilms.” 
- “The optimal temperature for enzyme secretion is 37°C.” – 98.6F (from wikipedia)
- “has proven to be an unexpected tooth decay fighter as it has the ability to cut through plaque or a layer of bacteria
- “Bacillus licheniformis is commonly associated with food spoilage and poisoning. It causes bread spoilage, or more specifically, a condition called “ropy bread” (1). Contamination with this bacterium will make the bread sticky and stringy; the ropy bread will also start to develop a strong odor after contamination. Rope spores is what causes the spoilage; unfortunately these spores do not get killed during the baking process.B. licheniformis can also cause food-borne gastro-enteritis, which is infection of the gut that can lead to a life threatening condition called septicaemia. Septicaemia is blood poisoning, and is classified as having a large amount of bacteria in the blood. Dairy products are at increased risk of being contaminated with toxin-producing isolates of B. licheniformis. Cooked meats, raw milk, vegetables, and processed baby foods are also at risk. (4)The symptoms include stomach pains, (acute) diarrhea, and possible vomiting. These have an onset time of 2-14 hours and last no longer than 36 hours.B. licheniformis, although usually associated with the gut and gastrointestinal tract, can also cause distress in other parts of the body. It can cause ophthalmitis, which is the inflammation of the eye. It can even go as far as causing abortions in pregnancies and impair sperm motility. The toxins produced by B. licheniformis can cause damage to cell membranes, deplete cellular ATP, and cause the acrosome to swell; it is not found to have any damaging effects on the mitochondria.” microbewiki
- is a lactic acid-forming bacterial species…separately isolated in 1935 and described as Lactobacillus sporogenes in the fifth edition of Bergey’s Manual, [wikipedia]
- No MicrobeWiki page
- Bacillus clausii, has been found to produce antimicrobial substances that are active against gram positive bacteria including but not limited to Staphylococcus aureus, Enterococcus faecium, and Clostridium difficile. [wikipedia]
- “The protease from Bacillus clausii strain 221, the H-221 protease, was the first enzyme to be identified in an alkaliphilic Bacillus.  The alkaliphilic nature of the organism has also proved it to be useful in preventing and treating various gastrointestinal disorders as an oral bacteriotherapy.  This organism can be found in many alkaline environments, including soil and marine habitat…Bacillus clausii resistance to many antibiotics makes it seem capable of harm to humans, but Bacillus clausii sporulated strains are actually used in the treatment of gastrointestinal illnesses to restore intestinal flora because of their antibiotic resistance and ability to stimulate immune activity” [WikibeWiki]
The two strains that are listed are newly discovered which carries the risk of unknown side-effects (just like a new drug carries the same risks). I prefer strains that have been in use for 20+ years. Bacillus Licheniformis (without strains) raises the question whether any herx like effect is actually a herx and not toxins or histamines that some people may be sensitive to. Bacillus Coagulans being the rare member of the bacillus family that is a lactic acid producer raises concern if lactic acidosis is a significant part of CFS for some patients. Bacillus Clausii (without strain) has the appearance of being safe and good.
My preference is the 4 bacillus Clausii mixture, Enterogermina. Far less uncertainty and risk of unexpected side-effects.
In terms of closeness in genetic distance
I came across a diagram showing how close (or far) apart the different ones are from each other in terms of genetics, The best one (IMHO) is clausii and it is a considerable distance from the rest.