Anti-sperm antibodies post vasectomy

  My husband has finally agreed to have his 16-month-old vasectomy reversed.  Our doctor is very optimistic about our chances for a successful reversal.  I have been corresponding via e-mail with some other people who have undergone vasectomy reversal and very few of them seem to be getting pregnant, despite adequate sperm counts.  Two of them recently had positive antibody tests which apparently means it will be difficult or impossible for them to conceive.  Questions are as follows:  Our doctor has not suggested having this test before the reversal.  Should we suggest it?  What percentage of men have these antibodies and why do they develop?  Are they more likely in men who have had their vasectomy for a long time?  Also, one woman told me their doctor told her they should still be able to conceive because her husband's antibodies were confined to the TAILS of his sperm . . . . can you explain this or did she misunderstand what she was told?  I guess any information you could offer regarding anti-sperm antibodies is what I am asking for.  We would like to be optimistic about the success of the reversal, but I don't want to be falsely optimistic.  Thank you for your time.
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Dear Eve,
As you are probably aware, the success of a vasectomy reversal is indirectly proportional to the time duration since vasectomy is performed.  However, there are other factors that come into play that may prevent successful pregnancy after a vasectomy reversal such as anti-sperm antibodies as you correctly mentioned.
Normally, the sperm are not directly exposed to one