We've tried rotation servers multiple times, and every time, they don't get supported and die off quickly. The initial week's interest from eGO members tails off fast, and we hurt every other server in the process. As soon as the map changes, people who hate the new map leave, and the server dies off. Established rotation servers do well because they have a huge population and are both well-known and highly-ranked; our community was built on Avalanche/Donner/Strand/Kalt. While the house system is gone, the inter-map rivalries persist, to a point.
We used to have Flash as well, but we had to cut it because the server was dead. People loved it, but it died off eventually.
We replaced Kalt with Argentan and Colmar, and neither of those took off, except for during official events. Anzio has been our most successful "new" server as of late, but it has required prolonged support from everyone to keep it going.
At the same time, we have limited resources and don't want to lose a top-75 server (which I'm proud to say that all of ours are!) trying something that has failed repeatedly. A rotation server sounds like a great idea, but it has never worked out, and that's why we have no plans right now to try one again in the forseeable future. Unfortunately, this is a case where the evidence has been very clear - we've failed every time that a rotation server has been attempted.