include ActiveModel::Validations does not make save check valid?. This may not be the best solution, but it seems to work. Note that Compatibility is included after this module; its #save method handles the :validate => false option.
# File lib/devise/orm/data_mapper/validations/active_model.rb, line 9 def save(*args) retval = valid? && super(*args) assert_save_successful(:save, retval) retval end