Countdown was good **** yeah
Definitely the best experience in organized matches I had, was excellent for small scale battles (max 10 players on each side, was working good 6vs6 too).
Unfortunately it wasn't working well in public games because people would not play it correctly due to lack of communication, inexperience, lack of knowledge of all the rules, respawn point, and so on. It was a wonder with a team or a group of people who knew the game mode correctly. All my public games were bad because people would do 'stupid' things when you could have won for example if the last guy standing didn't rush the attackers and die, or if your team wasn't camping near spawn instead of getting to capture zone when it was possible..
I think they made Skirmish mode kind of the successor of Countdown..
edit: I think RS 2 is definitely not made for clan matches, it is clearly made for public big scale battles. I didn't really have hope for the 'competitive' scene of RO 2 migrating to RS 2, and I never though the game would be oriented toward competitive players. Don't get me wrong, there will be always people trying, and maybe succeeding in playing clan matches, but I don't think the game fits that purpose.