I don't know about you, but if given the choice I would never use a bike path that was suspended 100ft in the air without some sort of enclosure, especially when there are countless parallel alternatives. It's not fear of heights, but as soon as the unimpeded wind starts blowing, it is a pain to have to fight it. The wind is also stronger at a higher relative elevation.
In the plan, the Gardiner's capacity would not just be maintained, but increased. This could cause severe congestion for the other highway sections that lead up to it unless they were expanded likewise.
The Gardiner and DVP should be tolled regardless of what new infrastructure is decided on.
While the PATH extension is a nice idea, you have to consider how much power would be used to maintain a 6km long greenhouse with no insulation.
I won't be convinced that the rail corridor won't be as much of a barrier if the viaduct is built until i see some street level renders looking up at the structure. It's this, and not the vista from a helicopter that people will see every day.