Besides the lack of popularity, are there any 'technical' or other unsafe issues with the 'Horndeski' method?

There's nothing new about breast reduction with short scars, internal shaping, or attaching the breast tissue to the pectoral muscles.  Good studies have shown that the suturing to muscle does not make a difference and that in good hands, short scar breast reduction and internal shaping techniques are quite good. There's nothing wrong with Dr. H and others marketing their practice, but there's nothing "innovative" there.  If the results hold up and speak for themselves then the surgeon is fine. Picking a surgeon based on a particular surgical method preference is like picking a lawyer based on the brand of pen they use or choosing an architect because they use Apple over Windows PCs. If you are serious about addressing this problem you should consider seeing a board certified plastic surgeon to discuss your options and find out if you are a good candidate for treatment.  Make sure your surgeon is experienced at breast surgery and that you research their reputation. If you like their results the. You don't need to be not picky about their method. 

There is nothing new about this except the name and branding.  The issue is the longevity of the result as well as its applicability to most patients.  Many short scar breast lift procedures have been around for years. Patients may think they know what they want in an idealized sense but it doesn't make any particular procedure appropriate for their situations.  Best wishes.

BabypicassoPlease Beware whenever a "New Cosmetic Procedure" surfaces, and only one surgeon does the procedure, and only that surgeon is able to achieve great results that cannot be duplicated by other plastic surgeons! As a breed, plastic surgeons are innovative and constantly searching ways to improve results, so if other surgeons are not offering the procedure, there probably is a good reason. Personally, I had to Google it to find it, and as far as attaching the breast to the pectoral muscle for support, it has been tried already in other breast lift techniques,and does not work. Consult me, or another board certified plastic surgeon in our area to see what your best options are. Also check out the link below to an article about the subject. Good Luck!