We were only 4 and stayed pretty close together, but there were a bunch of people around, so we needed text communication. My phone can only handle 5 connected devices throughout about a 250ft unhindered radius (100ft realistically), but if you had a real wifi network, you could add a lot more people and spread out much further.
E: we did have a member drop off several times because he was beyond the threshold, but he automatically reconnected when he got close enough.