Hi, I do check the ftp server regularly and look what date the current snapshot and the respective packages are of. If the packages snapshots have been updated since my last upgrade and the snapshots date and packages date are quite near together, I do update my system.
For doing so I use the OpenBSD-binary-upgrade script [1], then I update my packages. Until now that worked quite well for 99% of the time. cheers Earin [1] http://www.xs4all.nl/~hanb/software/OpenBSD-binary-upgrade/