I put on a set of the Eurosonic Ultra-Light strings. They seem very gut-like to me because of their sound and feel. They are a pretty thick string with very low tension. I am used to playing the Obligato strings and can play with a lighter touch at very fast tempos. How do most people play these type of strings at very fast tempos? They seem to have too much give and swing at a very big arc to have much controll over the string at fast tempos.