dont handcuff yourself like that. you are exposing yourself to the whim and fancy of psa and jsa if you do that. if an autograph that you know is 100 percent legit fails these services because they dont know the autograph, or that they just rolled out of the wrong side of the bed this morning, you are out a lot of cash, and it's not your fault. i would guaranee the authenticity of the autograph yourself, but a jsa or psa fail does not trigger your guarantee, rather real evidence that it is a fake autograph should trigger you guarantee.
josportsinc.com has a good guarantee disclaimer.
http://josportsinc.com/catalog/autograph.html
people i know have been burnt so many times by promising an item to pass psa or jsa, only to see these services get it wrong that we just throw up our hands now and say no way.