I agree with using XPath... if it's available. It is now available for XML::Twig but that's quite recent. Also in this case I used only accessors, but as pointed by ovid, I could have used setters or other methods.

And yes, it mostly "sweeps the issue under the rug", the same way Perl itself sweeps under the rug the fact that $ sometimes matches just the end of the string, and sometimes matches a line return and the end of the string. It might not always be the correct thing to do, it is just natural and convenient when you don't have to be too strict.

I really like ovid's comparison of the null object to the relational NULL BTW: sometimes you don't want the absence of some data to stop you, and you don't want to (and you should not have to) write a special case to handle it.