As an IAM'er I can only speak for my experience with them, the only road training I've done and, even though I've been riding a fair while, it was worthwhile in many areas. I don't apply everything (some by choice, some because I don't always remember to) but really helped with my hazard awareness and positioning for better view. Try their 'skill for life' package, you also get the chance to ride Thruxton once or twice a year.