Let's not go jumping any guns here folks - until there's an updated version of Canary, the server will still be 1.7.3. If it takes them more than a week or two, and the Bukkit guys beat them to the punch, the faster (though not easier, bukkit's a freakin admin nightmare) thing to do may be to switch over to bukkit. However, this will screw up how minecarts work (last I heard, minecart mania/craftbook STILL didn't handle minecarts/chests as well as they did on canary/hmod), and last I looked there wasn't a magiccarpet plugin for bukkit either. It will be a large ordeal to do the switch, unfortunately... especially the security end.
Really, copying over monuments would be the easy part.
Another note - we have the ability to run multiple "world" files (currently this world is described as "world 8" on our server). All I have to do to start us over from scratch is change a line in the config file (say, to world 9) and reboot the server. This would not delete Ragnar, and to switch back to it would just require the same change in reverse and another reboot.
There used to be a mod that let you change maps and reboot from a command entered in chat... if I can find it again, perhaps that'd be a stopgap solution. Notch had said in the past he thought the idea of making nethergates able to connect to different maps might be a fun idea, but of course it isn't implemented yet :/