good points howard, but if people are going to teach and say this is the east anglian style of billy bennington[hypothetical example] the best way to do that is either on that instrument or through recordings of billy bennington .
it would be ridiculous for me to try and teach carthys guitar style on my concertina, do you get my point.
personally i try and find my own style, and whilst i would listen to a lot of traditional musicians and singers and hopefully unconsciously absorb, going along to a workshop to copy a particular style doesnt really appeal to me, though i can see its uses as a stepping stone to developing their own style for people.so i supoose it depends how the pupil use the information.
there will always be people who want to faithfully copy oscar woods[that is their choice] but it doesnt appeal to me, however acquainting oneself with different traditional styles as a way of developing an individual style, that is more my cup of tea.