As posted on another site:
I recall an RNR PO back during TELIC who did immense good in a certain middle eastern country, and who got a CINCFLEET commendation for his work. The only way he was able to be so effective with the host nation was by making said PO a local acting and unpaid Commander, as that was the level the locals would do business with.
A lot of the time, the rank is essential if you want to be taken seriously by the nation - in ISAF SO1 is seen as entry level for many posts, regardless of whether its an SO1 or SO3 role...