I have finally updated the York Region Options page.
I provide two alternatives to building 4 km of subway between Steeles and Highway 7. The first keeps an LRT line underground for that portion of Yonge Street, but my preferred option is to come above ground just above Steeles (assuming an underground across-the-platform transfer with the subway).
This proposal provides 21 km of LRT for the same $1.4 billion the 4 km of subway would cost. This includes 10 km on Yonge between Steeles and Elgin Mills (including a 1 km tunnel north of Major Mac) and 11 km east-west line from Centre at Dufferin to Highway 7 at Woodbine.