There were about 14 or 15 of us off and on. Are these pylons not amenable to large communities?
Each player (or group of players working together) that wants to do ChC will need sixteen pylons, one of each color, plus anywhere from a few to a few dozen more to disassemble, depending on whether or not they use the item fabricator to duplicate the blocks that cannot otherwise be crafted and only generate in pylons. In addition, each player will need access to a variety of different biomes and the various worldgen plants and structures contained within.
From any point in the world of Minecraft (aside from oceans, at least), there will usually be one pylon of each color within a few hundred blocks (a few times farther than the player chunkloading radius, much to my annoyance), as well as several additional pylons of some of the colors, so granting each player an area large enough to get them all of the colors will be more than enough pylons for anything they will need to do.
However, that's not nearly enough area to cover all of the biome-specific worldgen plants and structures. Each player who wants to reach the end of ChC's tech tree must find and claim one of each worldgen structure (and once a structure is claimed, nobody else can claim it unless the chunk is regenerated), so each player will need a sizable amount of ocean, desert, and plains all their own. In addition, there are necessary plants in a number of different biomes (including jungle, extreme hills, tundra/taiga, swamps, and both of ChC's own biomes), but if I'm not mistaken, those plants can be transplanted most anywhere and will grow just fine.
Chromaticraft needs a lot of space, in short, but Minecraft has a lot of space to go around, so it works.