Hi, justy.
I can give you my perspective on the protocols, but I know that freddd has different views. I'll try to represent his thinking here, too, since he hasn't been around for a while, and I don't know if he will post.
In my hypothesis for ME/CFS, which is called the GD-MCB or glutathione depletion--methylation cycle block hypothesis, the key issue is that the enzyme methionine synthase, which joins the methylation cycle and the folate metabolism, is partially blocked. This was originally discovered in autism, but has been proven by lab testing to be true in ME/CFS as well. So the treatments that had been helping in autism were found to work for ME/CFS, also.
There are several of these methylation-type treatments in use now by various practitioners as well as a large number of PWME's/PWC's and autism patients. The key aspect of all of them is that they combine high-dosage B12, given sublingually or by injection, with at least RDA-level dosages of folate, usually one or both of the active folates, 5-methyl tetrahydrofolate and folinic acd, but in one protocol (Dr. Alan Vinitsky's) very high dosages of sublingual folic acid are used instead. The various protocols also include some other supplements, but the combination of B12 and folate are the common denominator. Taking B12 by itself, without folate, has been somewhat helpful to some people with ME/CFS, but to really get benefit, it's necessary to combine it with folate. That has been the breakthrough based on the methylation cycle block, which was discovered first in autism.
freddd himself has reported to this forum that he has inherited an inborn error of metabolism (a genetic mutation) in the intracellular B12 processing enzymes. This type of mutation is reported to be rare. freddd's cells are apparently not able to utilize hydroxocobalamin to make the two active coenzyme forms of B12 that they need (methylcobalamin and adenosylcobalamin). However, freddd has found that if he supplements both sublingually in large dosages, and also takes 5-methyl tetrahydrofolate (Metafolin) and some additional cofactor supplements, he can overcome this genetic problem and correct his symptoms. He has reported that there are actually many other people who respond the same way he does to the various supplements.
I have favored starting with hydroxocobalamin as the B12 form, and moving to methylcobalamin if there is no response. In my experience, most PWME's/PWC's do respond to hydroxocobalamin. In theory, methylcobalamin can methylate mercury and make it easier for it to move into the brain, so if a high body burden of mercury is known or suspected, I suggest starting with a low dosage of methylcobalamin and working up if it is tolerated.
freddd, on the other hand, reports that hydroxocobalamin does not work for him, or for many other people, and that methylcobalamin and adenosylcobalamin are the ones to use.
It hasn't been clear to me whether the people freddd has mentioned actually have ME/CFS, since his earlier experience was with people who suffered from absolute B12 deficiency, which is not the same as ME/CFS. In ME/CFS, there is usually a functional deficiency of B12, rather than an absolute deficiency.
Another difference between what I have suggested and freddd's approach is in the response to increased symptoms on the treatment. I have recommended that the dosages be decreased until the symptoms are tolerable. freddd, on the other hand, has favored maintaining or even increasing the dosages, in order to "push through" the symptoms.
Various people have reported different experiences with this. Some have confirmed freddd's views, by eventually feeling better, though their symptoms increased quite a bit initially. Others have said that they could not tolerate freddd's approach, and some have decided to use the lower dosages, as I have suggested.
At this point, I don't think it's clear which approach is best, and it may differ for different people. Unfortunately, there have not been any controlled clinical studies comparing these different protocols, so all we have to go on is biochemical theory and anecdotal reports from a few people.
I hope this is helpful.
Best regards,
Rich