Optimizing rsync for transferring huge files quickly
Solution 1:
It seems like you might want to take a look at the --whole-file or -W switch. This is enabled by default if rsync is doing local filesystem copies, but I think the docs recommend its usage if the LAN speed is high and syncing over the network.
Basically, it disables the rsync delta algorithm and just transfers the whole file if it believes it's different.
You shouldn't have to worry about checksumming unless you force -c. By default, it just looks at the last modified time and the file size, and assumes the files are different if those values are different.