I was involved in the selection process for the twins for DHFS and we were limited to those types proposed by the various companies tendering for the task. In addition to the roles Crab mentioned, the requirement was also for navigator training in a centre seat. That precluded the BK 117 where the control runs were through a large 'box' from floor to roof between the pilot seats. The other types were MD 900, AS 365 and AB 109. The 412 was the winner by quite a clear margin, the others either lacking cabin room or had wheels considered too small for soft ground running landings. Was fun flying all those types for a week though!