Glad someone is taking this on. Can't wait to see it on the wiki. Some other possible points of comparison:

• validation
  • does the package provide it's own system of validation rules, and if so, is the system customizable/extensible?
  • does the package support one or more third-party validation packages, and if so, which ones?
• form construction/definition
• does the package support config-file-based form construction?
• does the package support dynamic (run-time) form construction/modification?
• framework integration (e.g. CGI::App, Catalyst, etc.)

I second perrin's suggestion to review Rose::HTML::Form from the Rose::HTML::Objects dist. I haven't used it yet, but from what I've seen it has some unique and interesting features:

• form classes can include code for pre- and post-processing; you can embed methods to populate the form from objects and/or construct objects from submitted data, or you can embed your model/db interactions directly
• forms can be nested/aggregated with automatic fieldname subscripting; e.g. you can design a PersonForm for name info and an AddressForm for contact info, then display and process them as a single submission
• basic field types (e.g. checkbox groups, selectboxes) can be subclassed to create reusable custom field types with their own specific validation, input and output filtering, and even compounding of multiple sub-fields