I only avoided *buntu (and the other Debian releases) because it was hard to get the genuine, Sun/Oracle-based Java to work with them (no package-based install), and MineCraft at the time was *ahem* "less reliable" with the OpenJDK (this was according to Mojang...dunno if this has changed). At the time, I had no separate Windows license for a server machine, which is why I chose CentOS* (since there was an official "sponsored" RPM version of Java for RHEL, and CentOS is a RHEL fork). Once I got a Mini, though, everything got moved there and it has been smooth sailing since.
A warning about the backups. I would manually make them on the CentOS machine (Time Machine handles my OSX backups for me now), but you have to remember that Minecraft will have problems if it can't access the data files, so if you're running some sort of script, you want to make sure you turn saving of world data off while you make your copy and then reenable saving once you're done. Alternatively, you can shut down the server long enough to copy everything, but then people complain about the 15min of downtime...
--Patrick
*I know I said Fedora earlier, but I meant CentOS. I just got the name of my "Free Version of RHEL" fork mixed up.