When daughter and I went with a group on that trail ride last month, daughter and I used hackamores on our girls. Daughter used a nice little side pull that her horse has been trained with since she was started under saddle. I used a mechanical hackamore on my Dancer because that was all I felt she needed - she responds to it quite well.
One of the other riders told us we should be using bits on our horses on the trail rides, but she didn't say why. She did seem pretty upset that we were using hackamores.
I'd like to ride with groups again - it was a lot of fun. I sure don't want to upset anyone - though if bits are some sort of requirement, I may have to pass.