I personally know Sushi and Sergio and can confirm that they are Dr. De Meirleir's patients. I also know another KDM patient well, who has a good opinion of him and told me he was friendly.
I, myself, am not a patient of Dr. De Meirleir, but i think i will try to get an appointment in the next couple of months, because i don't know of many other doctors who have his experience with ME/CFS in Europe. And i need to try to get my case documented as thoroughly as possible, for legal reasons, so i'm looking for a doctor who knows how and where to find abnormalities in a ME/CFS patient.
I can also honestly tell you that my impression is that he likes to make some pretty bold statements (in videos, presentations, etc.) and that i, personally, would not necessarily believe 100% of them, before they are confirmed by solid results.
Nevertheless i don't think there are many better ME/CFS doctors around in Europe.