I am only in my 30's and do coach high school soccer so I should last a while!
In all honesty, the Guarantee is something I already do on a personal level and I am confident that my abilities in authenticating photographs is at least equal to anybody else in the hobby and I would put the sheer numbers of photographs I have viewed in person up to anybody's in the hobby as well. It is something nobody else in the Auction World is doing and everybody I spoke to about the guarantee advised me against it, but I will always stand behind the items I sell so for me it was a no-brainer.