Australia needs to grow up from the multi requirements, look at the US. all they want is x amount of turbine time as well as TT. The future is single-engine turbine PC12,208,KODIAK etc..Most of these piston twins haven't even been in production for the last 20+ years. If someone can fly these they sure as hell can fly a clapped out 310, they should be considered equal.
Its only about reducing sim time for new hires, that's it. If you have twin time and you are going to fly a twin, the sim instructor won't have to spend time training asymmetrics and twin engine management. Most training assumes you have a good grasp of multi engine operations and are just doing a type conversion and then line training to familiarise yourself with company procedures. Most of the sim training and check will be one-inop based under the IFR. Dash-8 or SAAB are just like flying a big Chieftain or 310 if you like, the engine type is almost irrelevant, what's important is they have two powerplants that provide asymmetric thrust should one fail.
I actually see turbine time a useless stat, turbines are piss easy to fly as long as you don't cook it on start. Even signing off for pressurisation is very easy, as the systems on airliners are pretty much automated with very little pilot input.