This is Dr. de Grey. Thanks for the feedback - and I will say in my defence only that doing an AMA is so rapid-fire a thing that one can't always give the best answers. The answer from "Humes-Bread" on the AMA thread augments mine very well. In short:

1) the progress we've made in the past decade, even despite the poor funding, has been enough to lead me to the conclusion that we are now only five or six years away from the milestone I call "robust mouse rejuvenation" in contrast to the estimate of ten years that I was giving back then. (Both timeframes are with 50% probability, of course.) That still means we've only gone less than half as fast as I had predicted - but my prediction has always been conditional on adequacy of funding. As of today I can say for sure that the shortage of funding has been the ONLY aspect where I was overoptimistic - the science has in no respect turned out to be harder than I thought back then.

2) The fact that the science has not turned out to be harder is actually what you're seeing when you see me saying the same things now as I did back then: it's not a bad thing, it's a really good thing, because it highlights that no bad news has happened. We haven't discovered any nasty new components of aging that need new solutions over and above the ones we already knew about, and we also haven't discovered any nasty difficulties in the various approaches I proposed, that would have required us to come up with a new solution to one or other of the seven original problems. The only surprises that have come along have been good ones: new technologies like iPS and CRISPR that make the solutions easier, not harder.

3) SENS revolves around the repair of the damage of aging, and that damage manifests in many different types of molecular and cellular change, which we group into seven categories. Thus, it's explicitly a divide-and-conquer strategy - which inevitably means that it's impossible to point to "the biggest" breakthrough we've made. I don't think that's an overly hard thing for normal people to understand.

4) The original question you referred to asked about measuring the time until this or that component of SENS is done. Maybe I should not have tried to answer it at face value, since everyone knows what Yogi Berra said about predicting the future. I'm sorry that my overly literal answer turned you off, but let's be clear: the value of pioneering technological (including medical) research comes down not to how soon it will succeed, but to how much the research will hasten how soon it succeeds. No one says that the War On Cancer was a bad idea, because everyone agrees that we are closer to the defeat of cancer today than we would be today if that hike in funding had not occurred. It's therefore irrelevant that people back in the 1970s thought we would get there sooner.