Some brief initial comments...
MobbsClearly this is the least interesting challenge, from the counter response its hard to tell if they even read Aubrey's rebuttal... They also seem to have the (obviously) mistaken impression that SENS is calling for a hault on all basic research.
WeinsteinHere at there is at least some interesting ideas presented. However the consistent theme seems to be that additional problems would crop up after an initial increase of maximum lifespan achieved by SENS. However difficult one may expect those additional problems to be, they are already admitting that some life extension could be achieved, which certainly disqualifies him from winning the challenge.
EstepThe best contender, or at least the most adamant... they correctly and repeatedly point out that SENS is very optimistic, but that in itself does not discredit it from scientific discussion. For example:
de Grey’s “arguments” that accumulation of heterogeneous waste products in lysosomes can be dealt with in a manner similar to therapies for lysosomal storage diseases, do not constitute proof in the least
Obviously SENS is not a 'proof'... its an educated guess and proposal to solve a problem which
is solvable but for which the difficulty cannot be fully predicted.
As far as I can see, none of the entries meets the challenge. They all focus on what could be wrong about SENS, without aknowledging that the best way to find out the truth is to openly discuss and research the proposals that SENS makes.