Modern is better for keeping up with peers who are using modern. Over a "long" ride, optimal cadence provided by a wide range of closely spaced gears saves energy required to avoid getting dropped. Modern dual pivot brakes also save energy and allow me to hang tight in a peloton and not get squeezed out the back. Some cyclists using vintage components could hang in a modern component using peloton but they would have to posess superior skills and/or be stronger to be there at the end.