Those are really the same model, except the Pike way calls trunk 7.odd for increasing odd numbers (and rarely, new majors), over time. I, for one, think the signal value of that is enough to merit sticking to the same directory structure in svn, as svn doesn't care either way. That way, you can tell apart a checked-out "trunk of 2003" from a "trunk of 2007", at a glance, just through a quick peek at the directory name (and swiftly do away with the old after a check for uncommitted code).