You're joking, right?
~20 servers are pretty much for a mod not listed in steamworks.
I've just browsed through a few other mods
Dystopia: 19 servers (and it's listed on steamworks)
Jailbreak Source: 7 servers, noone playing.
Kingdoms Collide: 3 servers, noone playing.
Neotokyo: 10 servers, noone playing.
Orion: 9 servers, noone playing.
Project Valkyrie: 1 server, noone playing (sadly).
Stargate TLS: 3 servers, noone playing.