I haven't done anything like that myself but my auntie did the IAM course and thought it was worthwhile. A lot of the people that do the courses are or were police riders so they're bloody fast but always riding within their limits and to the current conditions. I think they're more about looking for dangers, picking up on little things which indicate whether there's a tractor round the corner or whether the corner is about to increase in radius or decrease etc.
P.S. This may be the wrong forum for what you're after...