Subversion is actually quite popular with RoboHelp authors. Start with this excellent article:
Then, search the Source Control sub-forum for more info.
Adobe Certified RoboHelp and Captivate Instructor
I've used subversion on a couple of online help projects. It has the added advantage of integrating your workflow with dev team. You can check in your work directly into release branches or trunk for example. It is going to depend on your specific setup on how this works for you.
I use svn outside of Robohelp's source control and just check in ALL updated source files at end of the day.
I'm less vigalent with the output / webhelp files and just check these in when I need to check the output and close to the release dates.
Once you get over the 70s interface it grows on you.
If you have any specific questions just let me know.
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