We decided to move the method validation methods into a separate interface for a better separation of concerns. That way the Validator interface doesn't get overly complex for a user who is only interested in plain bean validation.
Related discussion on bv-dev: http://lists.jboss.org/pipermail/beanvalidation-dev/2012-September/000534.html
From the discussed approaches for retrieving the method validation delegate (see discussion on mailing list) we went for the getter approach, that is, a method forMethods() which returns the delegate.
Compared to the discussed fluent approach the getter appraoch avoids repeated creation of method/constructor specific delegate objects which is an advantage performance-wise. Retrieving the validator from ValidatorFactory seemed disadvantageous regarding the configuration of validators and retrieval of constraint metadata.
Still unhappy with the use of the word delegate but I can live with it and can revisit later