in reply to Is this code which is using Switch.pm safe?
Rather than provide links to pages that may cease to be, please provide small samples of your code inside <code> tags in your node.
The Switch module is a source filter which is something to generally avoid for production code. If you can't use 5.10 or later and given/when then I'd strongly recommend one of the other alternatives to switch that you mention. Depending on what your code looks like, I'd tend toward a dispatch table.
True laziness is hard work