Normally I use my iMac as the main computer, but when it went forth and back because of various problems, I needed to sync more seriously between my iMac and iBook. I could not figure out how to use RetriSpect for that purpose, and started using ChronoSync. It works great. I now have several containers, called iMac2iBook or iBook2iMac, which sync my databses, documents, and sometimes additional files.
On paper, I did not realy want to use the FireWire target mode. In practice, I have discovered that it works like a dream.

The only thing I need to remind myself of is to eject the target HD before I disconnect the two computers. I would have liked a warning from ChronoSync upon quitting.
A second item on my wish-list would be an overview of only those files which are to by synced, without those which will not be synced, in the analysis window: now I have to expand all folders manually and wade through a large number of files to see which files will be affected by synchronization.

But these wishes are not essential: it works well. Highly recommended.