Perfect--does exactly what I wanted (and no more). Handles all buffering through the filehandle for free. slurp method gives me the Perl object a la JSON after I have set the cursor using the pull API. Thanks!
Bio::Phylo is really a complete solution not only for phylogenetic manipulation, but serialization and analysis as well. The author's NeXML phylogenetic markup standard is fully integrated into Bio::Phylo, so that users will be able to transparently incorporate this emerging standard into their applications. BioPerl has also plugged into Bio::Phylo; BioPerlers interested in trying Bio::Phylo's NeXML capabilities will find an easy way into Bio::Phylo using the Bio::NexmlIO wrapper. The package is complex and thorough, this does give class navigation a steep learning curve. POD is complete and contains overviews, however. (Full disclosure: I have participated in Bio::Phylo development.)