I watched Dr. Sherwin Nuland (considered one of the three finest M.D. authors in the west) on C-Span and the subject of life extension came up in the interview. He felt "compressed morbidity" or the reduction & management of age-related breakdown until the very end of life was what we should be aiming for, and not life-extension (anything beyond 120 years in his view).
The reliability theory of aging suggests that any effort to compress morbidity will ultimately produce healthy life extension: all age-related degeneration is the consequence of acculumated cellular damage. Efforts to prevent and cure age-related disease will prevent or repair some of this damage, thus extending life span. Quite aside from this consideration, one has to look askance at this rather odd end goal: to aim at accomplishing an arbitrary healthy life span and then just let everyone die rather than continuing to explore the infinite possibilities offered by advancing medical science.
Nuland said he had recently spoken with Aubrey de Grey and went on about de Grey's plans for greatly extending lifespan (which he said were somewhat vague and not fully worked out yet) with a tone that was surprisingly almost friendly or at least neutral. The doctor calmly stated he disagreed with de Grey's goal of a human lifespan around 5-10,000 years. lol I wondered why de Grey had the arbitrary figure of 10,000 years as his finishing line. Why not 100,000 years?
This projected goal for human life span comes from a consideration of the fatal accident rate in a world in which death and disablility due to aging have been conquered. You'll find a further elaboration on this figure in Chris Lawson's The Tithonus Option is Not an Option. None of Aubrey de Grey's projections and goals are in any way arbitrary; you should take a look at his Strategies for Engineered Negligible Senescence website for much more information.
As with many doctors, Nuland wants to maximize life expectancy rather than expand lifespan. I did find it interesting that he said Leon Kass (who he claims to admire for his academic achievements) was too far right of the spectrum, while he himself was "just right."
You may recall that Nuland was the author of the rather obnoxious Technology Review article on Aubrey de Grey's work. He's in much the same boat as Leon Kass when it comes to healthy life extension technologies, but without the calls for government intervention to block their development and use.