My understanding is that the new PTL system (Metron) will apply to all aircraft inbound to Perth. All aircraft departures will be "controlled" ie if you're trying to taxi early, you'll be told by ATC and suffer the consequences (eg enforced holding if you dick another aircraft around) if you decide to depart early.
Be interesting to see how that works. There is currently no mechanism for a controller to know what an aircraft's slot time is. I also doubt for example that the Singapore Ground controller will be telling aircraft they are taxiing early. Plus how do you know these things and we (ATC) don't!
The problem with shafting the cheats is that its much more work for us. (I know, boo-hoo, public servant whinging about having to work!) With extensive holding the arrivals sectors can be right on the edge. If we than have to hold some plonker for 45 minutes while others go through the pattern it could be enough to push it over. Many feel though that we should though, because we would only have to do it once or twice before the message got through.
As if an extra 40kts over 5nm is going to make any measurable difference!!
A 'speed up' is usually about who is behind you, if another aircraft is 4 miles behind and 40kts faster it makes all the difference in the world.
The thing to bear in mind with last minute changes is that the procedure relies on aircraft crossing the fixes on time pretty much to the second, which is beyond the capability of most of our traffic. If number one is 30 seconds late and number two is 30 seconds early, we have to intervene to maintain separation. I would never claim that we don't sometimes make a pigs ear of it though.