Separating xowiki::Form from and xowiki::FormPage is a certain challenge. When i have some more resources free, i can try to address this problem, maybe together with the xotcl 2.* transition. But as a first step, we need the release of a non-beta version of xotcl 2.
Trying to subclass the Note demo under e.g. xowiki::FormPage does not make much sense. It is much easier to define the fields you want for the Note example in a xowiki::Form, configure away the fields that you do not want, and use "fill-out" to create instances. If you need fast access to the form fields from the database, use hstore. One drawback is that you get this way the semantics of the content-repository (with e.g. revisions, search integration, etc), which you might not want. If you want more control over the submit-buttons, actions, etc., use xowf.