Thank your for your points!

I'm writing a module that calculated estimated time of accomplishment. After it is ready I'm planning to release it as Time::ETA. It is not complete, but you can look at the current version at github.</>

With this module I'm solving a hi level task. I need to create web interface for long lasting tasks. I'm plannig to store serialized version of Time::ETA in database to make it simple to output current status. I think it is good solution — I hide some logic in CPAN module.

You are right that it will not be possible to search through this data, but I here I don't need it.

You are right that YAML can't serialize a lot of thing. But some things can't be serialized in any way (for example open filehandle). In the module I'm going to serialize several scalars, so YAML will do it's job fine.

I'm not doing to support multiple serialization formats I just want to have backward compatibility.