I did a recording just this weekend of an evangelical gathering of 30,000 plus people with Angus Buchan (Faith Like Potatoes) in an open field out in the countryside and I used a Sanken CMS9 Stereo mic recording as a stereo pair onto my Sound Devices 552. I also used a Zoom H4 from the stage, next to the onstage mixers booth, pointing at the crowd. Finally I used my Senheisser 816T as well. I used the 816 and the CMS9 from various perspectives around the crowd to see what sound I would get and I am very happy with the results. All three configurations gave me satisfactory recordings of what I needed, though the Zoom H4 does sound a little thin in comparison to the other mic's.
Experiment and you'll quickly find the setup that works well for you!