Clera (the Welsh Traditional Instruments society) and trac (trac-cymru.org) both run workshops and projects which focus on transmitting music - vocal or instrumental - aurally. The "value" is partially in knowing that you're carrying on a tradition. However, I think there are other education arguments that can be made. For instance, I've seen non-academic children and adults respond tremendously to aural transmission (in one case, a very autistic young man) and it obviously also has value to visually disadvantaged musicians.

I also believe that the skills required to learn aurally are different from those that depend on written music. When I have to make a case for our work with funding agencies that are mainly economic or community development oriented, I claim that people who can successfully learn aurally tend to be more entrepreneurial in nature, able to respond more rapidly to changing circumstances (think 'sessions' - you have to adapt quickly).

Of course, I don't have any proper research to back this up (yet) but stating something with conviction can often carry the day with 'suits'.

siân