A key difference between the RAN and the Army with MRH is that the Army needs a battlefield helicopter, not just a helicopter to get from A to B. The MSH role is pretty straightforward, and the MRH has a lot of excellent capabilities (when it is working) that make it very suitable to the role. Conducting air assault is, of course, a much more challenging assignment, with SF needs being a step above even that. This was a key reason why the RAN was able to get more out of the helicopter quicker - the operational role just isn’t as challenging.
An example of this is that the MSH flight on the LHD can’t be used for air assault tasks, or indeed any task that would see the helo land in an unsecured LZ. Even though the airframe is identical to the Army airframes embarked on the same ship, the crew just doesn’t have the skills needed for the role (of course, they concentrate on other skills, like landing/winching from small floating LZs in the middle of the ocean). So you might see a lot of airframes lined up along the deck of an LHD, but if one of those is the ships MSH, then the amphibious assault capability of the ship is much reduced.
There is a similar dynamic with the NZDF, who haven’t really tried to push the envelope the same as the ADF birds, which is one reason you hear far less complaining from that side of the Tasman.
For example, ngatimozart spoke above about an ex in which grunts disembarked down the ramp with door gunners in the doors. That’s workable for air mobility tasks, but isn’t really an option for air assault tasks due to the spinny thing at the back of the helo getting in the way. A single disoriented grunt or patch of uneven ground makes that a disaster waiting to happen. Hence, we’re back to finding a place to put the guns so you can disembark via the doors at the same time.
If we were looking at the Navy getting more MSH, it would make far more sense for them to get more of the Army pool of MRH, with the ARMY backfilling with useful battlefield aircraft instead (more chooks), than with them getting a new buy of MRH or a different aircraft type.
As stated, 6 Avn will be re-equipped with MRH in the near future, replacing the Blackhawk. They were told they could have either new blackhawks or a new light deployable helicopter, but not both. So they chose the light deployable helicopter and the Taipan.
