The reason the Melburne uni one is longer is they make you do more breadth subjects and have a really flexible under graduate degree. Personally, seems like a bit of a work around just to make more money but it does have some real benefits, mainly it fixes the problem of kids going into a course, then finding out they hate it and then being left adrift about wth they r going to do.
The job prospects r bloody fantastic for engineering, literally all the engineering fields u mentioned r growing. I think RMIT even introduced a new space engineer course this year lol.
But anyway, prehaps you could also consider Swinburne? A physics teacher of mine was taking about them and said that at monash and stuff, graduates will walk out of their with an amazing grasp of the theory, which is all well and good but swinburne places a heavier emphasis on actual, real life experience with engineering. It is quite good (obviously u still learn a ton of theroy, just they allow you to get real world experience, very useful for equipping u for a real job. So if u haven't considered it maybe look at Swinburne?