I'm in Bacchus Marsh, 15 minutes out of Melton. I might be able to add a bit.
Toolern will be on the SouthEast edge of Melton, right now the major attractions are a new TAB race track which clogs the freeway exit on Friday evenings, and the local tip.
The railway line runs through the middle of Toolern, and it is urban rail, not rural. Should be an easy matter to bang in a station, though they'll prolly make people use the station in neighbouring Melton South for a while yet.
While Melton South has the railway line, the other side of the freeway has all the good mediacl, shopping, leisure centre and better housing. I'm guessing it will be a while yet before Toolern attracts better shops and facilities. Education would also be an issue as there are more schools on the other side of the freeway, the western suburbs has very few good public schools and the state govt has a policy of merging schools into megaschools. Not sure what they will do here but as a parent I would rather sit back and watch this develop.
There is new road infrastructure making Melbourne about 45 minutes away from Melton. Toolern might be about 3 minutes closer than that. The Melton facilities will be 10-15min from Toolern.
My best bet would be that the beginning of Toolern would make Melton proper a great prospect. Toolern will bring even more people to the area, but people will still crowd toward the facilities. As it develops Toolern will get it's own facilities, then it will be worth a look.
Looking further into the future, the whole area between Melton and Caroline Springs will be gradually openned up to housing over the next 30 years. It's a massive area. There will need to be another entirely new shopping precinct, probably around Rockbank where there is currently a tractor dealership and a smattering of houses. There is a question mark over all that land because the goverment want to tax sales to developers to pay for schools etc. Quite clever because in the one policy they've kept a lid on land prices, enchouraged developers and raised money for infrastructure (but racked off land holders). Makes me wonder whether land banking could work here because the tax is fixed per hectare so in 10years it will have less effect on your profit, even though it keeps values in check for now.