This summer in England at a fiddle-festival I played for the first with an Arcus bow. Only the very first strokes got me enthusiastic. Especially for Irish folk, which is what we play a lot, the Arcus is perfect, as it allows the fastest string crossings due to its low weight. But also Slow Airs can be played most beautifully because of its instant response and round sound.
Many passages that used to be very difficult to play with a normal composite bow, are now perfectly normal and easy to play.
Back home I decided to buy a Sonata. The bow pulls a completely new sound from my fiddle, as all side noises have disappeared, even the low c-string on my 5-string fiddle response really well. But it is not only important for me to make a nice sound: The lightest push with the index finger suffices to pull this meaty sound as is so important as an element of rhythm in folk music.
Especially the octagonal bow works very well for me with its fast reaction, and allows me to play difficult rhythmic elements of which I had never expected to be able to play them."