The no aeros FI restriction has always been a big anomaly - I don't know whether there has ever been an incident / investigation where an FI has been teaching aeros who hasn't had the restriction removed?
Genghis - don't get me wrong, I have flown with a number of CRIs who are very capable. Equally I've flown with a number who aren't even up to PPL test standard. I think the key is the attitude of the individual - someone who keeps their skills fresh, keeps up to date with legislation, knows their limitations and learns from / is supported by more experienced instructors etc.. will be fine.