From the poll I cited:

    The maximum sampling error estimates for results
    based on the overall sample of 834 registered
    voters have a sampling error of +/- 3.5
    percentage points, while findings from the
    random subsample of 415 voters have a sampling
    error of +/- 5.0 percentage points at the 95%
    confidence level.

http://field.com/fieldpollonline/subscribers/Rls2443.pdf

FiveThirtyEight rates Field Poll (at least for political races) as being "A+": http://fivethirtyeight.com/interactives/pollster-ratings/

Your references to incidence of HIV and syphilis among gay and bisexual men are something of a non sequitur, and—I think—underscore the value of extending the institution of marriage given that one might reasonably expect that enabling an at-risk population to engage in a social institution commonly associated with monogamy should only serve to decrease rates of transmission.

    My friends (who are gay)

http://rationalwiki.org/wiki/Friend_argument

Also, why would you want your friends to be deprived of a right you enjoy?

I regularly see billboards in my neighborhood targeting young gay men to be tested for HIV. I bet that risk of transmission would be further lowered if the stigma associated with being gay was further reduced or entirely eliminated.