I am enjoying this game better than I am L4D2 and spent about 1/4 the money on it ... go figure.
All of my perks are Level 6 except Medic (Level 5) and Berserker (Level 4).
The Militia has a private server for the members of the clan. These are srcds servers and there are 5 of them for the different games we play. It is a lot more fun than listening to the pubbers beg for money all the time.
The KF server is on "Hard" difficulty and it is a long game (10 waves). There is a map vote with 111 different maps on a fast download site.