OM15, I agree with your comments regarding IOM, the staffing requiremnts for a subpart G will not be based largely on the number of Jets (20-30) but more the different types as similar types will be far less onerous to research and control.
All AOC operators are subpart G approved, not many PART145's are yet but if they want to retain a Technical services and planning function for ARC recomendations and control Aircraft within the famous 'controlled environment' then they need to crack on,
Below 5700KG subpart F etc will struggle the costs are huge, BJ at the IOM can not open his post quickly enough!
TMAB