I have tested this a lot and I do not notice a large difference between Dextrous Etude and Sword Madrigal. Both obviously decrease the amount of misses, but it is hard to judge which is better by scanning the log.
Usually if I ask another bard (>32) they swear by sword madrigal, but maybe that will change with the Etude +2 instrument. (I'm not up there yet)
My approach as bard is... - if there are a lot of misses, then Sword Madrigal and Dextrous Etude...the bottom line is that the melees HAVE to be able to connect. - if there are infrequent misses, then Valor Minuet I and Valor Minuet II (rarely the case in xp parties) - Otherwise I will sing VMII and alternate between DE and SM (to continue my testing).