The O/L will certain have to clear wires on an overhead basis at the bottom the valley.
The White Lines below show most of the wires, but a further set exists along the access road in between.
View attachment 331705
This is the elevation of those wires once they reach Millwood:
View attachment 331706
At that point, you would really prefer to cut over before they reach that height, which is what they intend on either routing.
The new routing appears to have them cross Millwood pretty much at the lights at Thorncliffe.
While the previous version would have been slightly to the south (the extreme left of the picture below or just beyond.)
View attachment 331707
I don't perceive clearance to be a big issue ( I could be wrong)
I imagine the issue was where and how to build the columns on which the bridge/guideway will sit.
Again, that is speculative on my part.