Hello,
at the moment, aspect forms are only supported as dynamically mixed-in form configuration for existing nodes. They will not work on model-type forms and - last I checked - you cannot reference an aspect form from advanced search configuration. Besides, the Repository FormService should fail when asked to generate a form, since it does not support aspect-only forms.
You could add the necessary support by proviuding the appropriate FormProcessor on the Repository tier and adapting the Form components on the Share tier, but this is a not-so-trivial endeavor on very different layers.
Regards
Axel