As long as implementors are tidying up this kind of thing, I suggest they also adopt the rule that in an r7rs syntax-rules form that specifies the identifier that will be interpreted in the rules as an ellipsis, it is an error if the same (bound-identifier=?) identifier is simultaneously specified to be interpreted as a literal.
So,
(let-syntax
((m (syntax-rules ... (...)
((m x y ...) 'ellipsis)
((m x ...) 'literal))))
(m x ...))
=> error
(let-syntax
((m (syntax-rules ::: ()
((m dots) (let-syntax
((n (syntax-rules ... (dots)
((n dots ...) 1))))
(n dots))))))
(m ...))
=> 1