I do not like where this station is located... at all, and it comes down to one simple reason: Regional GO busses.
Tell me, how are GO busses meant to serve this station? I guess they could get off at Dufferin/Keele and make their way to the station, but that'll be extremely slow. Now it seems like Metrolinx realized this, and as such only 2/6 GO busses along the corridor will service the station, but this feels like more of a bandaid than an actual fix. The Barrie Line is going to be one of the most important transit lines in the region, and relegating it to a bunch of local go bus routes seems extremely shortsighted, it'll arguably be a lot more useful than Highway 407 for what its worth.
Here's an idea, why not instead build the GO station on the south side of Highway 7, that way you can build some curbside bus stops along the 407 that GO busses can serve directly that would allow pedestrians to only need a short 2m walk to reach the GO station, and would allow busses to serve the station without adding an extra 5m to the schedule. And, you leave room for the eventual 407 Transitway/Ontario Loop to be built cheaply along the 407, rather than having to build an expensive underground diversion.