>>It is most likely quackery
I don't think quackery. There's real science behind it, but often the promise of science takes a long time to realize and there are many false starts and dead ends.
When my wife got her doctorate, the commencement speaker was a senior scientist who talked about fashion in science. He made the point that in the late 1970s and early 1980s it was almost impossible to get funding in his field unless you had a gene therapy slant. By 2002 when she graduated, he noted that you couldn't get funding for anything that did include gene therapy and the great promise had fizzled. It was only in 2006 after 34 years that therapies started to look promising, but even today it's considered experimental -
http://en.wikipedia.org/wiki/Gene_therapyKurzweil and de Grey always focus on exponential progress and that's true. My wife's major professor was one of the first people to do PCR and basically had to sleep in the lab and manually move things to sequence DNA. It was huge. By her era, you just plated it and put it in a PCR machine and had a sequence by morning. By the time she was done six years later, people were sequencing arrays of about 1000 sequences at once. Who knows where we're at now, but the cost in time and money has shrunk to nothing for a given sequence if you're doing them at scale.
But translating that to medical knowledge and longevity effects is a much slower process.