Definitely cards; especially if its a 'rock/pop' type of audience omnis would be pretty useless that far back unless you're trying to record the crowd with the band in the background. I love the CA14 > 9100 but from that far back it might come out pretty thin (and still pretty chatty) if the PA isn't super loud, and are we to assume this will be relatively low-pro?
Many people can chime in here better than I, but I'd use cards, put the 9100 gain at max and most likely add relatively significant gain from the recorder to get decent levels, depending on what you're using.