I do a lot of choir work. In the last month I have provided for at least six different choirs from approximately 7 year old to young adults and I have another choir next week that is made up of 2nd grade kids.
One of the concerts we did this month was the All-State High School Jazz Choir Concert here in Arizona. This included three different choirs for the concert. Two were jazz groups singing into individual mics. All the singers had SM58s. There were 20-23 kids in each choir. The third group was a "Show" choir with 40 kids that had choreographed dance while they were singing. We used 7 SM58s across the front. The mics were strategically placed so the stands could be used as markers for the dance routine. It worked absolutely perfectly. We chose not to use hanging condensers for this particular concert but have done so in the past for Show Choirs in addition to the 58s. They all had a live Jazz combo for the music and we used condensers for the Piano, guitar and drums, while we used good ol' SM57s on the brass and woodwind.
People really over think the choir stuff. If you aren't recording it then keep it really simple and use your 58s. You'll have a way easier time with monitors and it will still sound just fine.
BTW, I have four of the "Real" Oktava MC012 mics mentioned earlier and they are the mics that I would typically hang above a show choir. I love them, they work and sound great. Very hard to get the real ones now days though.