I've got the book but never got round to reading it properly. I followed the FIR + supplements protocol for about a year (indirectly under Dr Myhill via another doctor), as well as making a lot of other changes to diet and lifestyle during that year, and whatever it was that did it, all my symptoms improved dramatically during that year. I also had a bunch of tests from Biolab which broadly confirmed most of the sensitivities I suspected. I still don't really know what were the key factors for me, but it did seem that the FIR sauna was very important, and that subsequent identification of food sensitivities and environmental triggers was also very important. I am now largely symptom free so long as I avoid all these triggers, but if I eat the wrong thing or get exposed to the wrong thing (like molds every autumn and spring) I relapse very quickly and soon have fatigue, muscle pains, loss of concentration, etc etc - it only seems to take a day or two to bring me back down and a week or two of heavy detox, saunas etc. to pull myself back out again. I didn't really start to feel benefits from the sauna etc until after a few weeks, and then the improvements seemed to be quite sudden and sharp progress following 2 or 3 particular sauna sessions that seemed unusual (pattern of sweating was different).
I still don't really know what it all means, and I'm very cautious about concluding that Dr Myhill's protocol was what helped me, but I would certainly recommend it to anyone because it certainly seemed to be beneficial for me. My tentative conclusions - the model of how I think about it - is that each individual has a particular pattern of sensitivities, of which there may be very many and it can take years to identify them all; some are extremely hard to avoid entirely, and there are (non-standard) tests that are very helpful with this identification process (food sensitivity and environmental sensitivity testing would be my top recommendation for a worthwhile investment btw). The effects are very cumulative, so it seems to take a long time to gradually detox from these triggers, and until you are 90% detoxed and have identified 90% of the triggers it's very hard to notice any effects. Once detoxed, however, it became much easier to identify triggers - ie. from a position of being basically 90% well it became possible to notice the factors that made me worse again. Since then (a few years) I've continued to identify triggers, and I'm still doing so. I still react in exactly the same ways to all my triggers as I always have done, and relapse to classic CFS symptoms quite rapidly if I'm exposed to triggers for a few days. But so long as I manage to stay away from everything, I'm very functional. Needless to say, conventional allergy testing hasn't confirmed any of the other blood tests, but the tests I've had are absolutely consistent with my experience both before and after I had the tests so I do trust that they are right - for example, blood sensitivity tests a year ago listed all the things I believed I was sensitive to, plus a couple more sensitivities I hadn't found which I've since eliminated from my diet with beneficial results. Needless to say, my regular doctor thinks all those tests and theories are very dubious and doesn't believe any of it - and he also thinks I'm a bit odd for following this strange unscientific protocol, and that behaviour is evidence for him that CBT may be appropriate. I, on the other hand, see my patient behaviour as being quite rational: I see one doctor who has no clue what's going on and can't help me in any way, and I see another doctor who claims to understand it and actually helps me dramatically. Call me unscientific if you like, but I still think the doctor that's able to help me has a bit more in their favour, and I don't really care what the officially-santioned science says if it doesn't actually work for me.
I made a decision (or came to a realisation), many years ago, that for me I had to proceed on the basis that in reality I had no doctor and I was completely on my own with this. I took it as my own responsibility to investigate the options available, to experiment myself with what worked and what didn't - to be my own doctor and do my own science and to place zero trust in the official bodies. It was a turning point for me, and I've been getting better and better ever since. I found Dr Myhill's work to be the most convincing I could find (that was available to me in the UK), and in practice I found it very effective. It overlapped with a lot of other good advice from other quarters, so it seemed to make sense, and it seemed to work out well. Any one of the things I did, and still do, may be irrelevant, but by trying everything I could find, for several years, eventually I seem to have found my way out. Who knows, I may have gradually recovered anyway, and I may never have had XMRV, or never have had ME, but for me, avoidance of triggers, avoidance of exertion, FIR, and supplements (and a whole lot of anti-inflammatories btw) have been the way forward. But as a final word on it, I doubt that this process can succeed without a lot of dedication: I had to take some pretty extreme measures for many years before I made real progress. Basically, I do think you have to take a lot of responsibility for managing and investigating it yourself, and even then, maybe I was just very lucky (albeit that I'm still left it a situation where I can't leave the controlled environment of my flat very often, and can only eat a very limited range of foods, or I will rapidly relapse).
One more thought while I'm writing about all this period of my life: another thing I found incredibly helpful during this period was Shiatsu. My practitioner was a lovely person, and what I loved most about the approach was the holisitic nature and the quality of the therapeutic relationship. A one hour session encompassed a degree of counselling, discussion of symptoms, stacks of recommendations for foods to eat/avoid, supplements to try, etc etc (based on Chinese medicine principles) followed by a massage (the practical bit of Shiatsu). The main reason for mentioning Shiatsu here is that one of the things that happens in the massage is the therapist basically is gving your body a good workout, exercising the muscles etc, stretching everything out, but you just relax and meditate while they do that. I didn't experience any fatigue after these sessions (in fact I always felt incredibly peaceful, whole and balanced after each one - an effect which had largely worn off by the time I'd driven home unfortunately!). So it seems to me that Shiatsu massage may be a very good thing for people who aren't able to physically exercise themselves, because it can potentially keep your body active and healthy in the absence of that exercise: obviously there are consequences from not being able to exercise, and for me at least, Shiatsu appeared to help avoid those consequences. I'd be really interested if anybody else here has any experience of Shiatsu, and whether they felt post-exertional malaise after sessions or not, because if not, it would seem a very good thing for PWCs to explore.
In summary: based on my experience, I would recommend FIR, detox, Dr Myhill, and Shiatsu without hesitation - the only qualification being: always try to objectively assess what is and is not effective for you as an individual and - while giving each protocol a fair chance - don't spend too long on dead-end treatments that aren't working. Cast the net wide until you find something that works for you. None of it is cheap though...