I'm not concerned about the Bridle Path's property values, just that it represents a significant obstacle (which means $$$ to overcome). (However, since you bring it up, neighbourhood opposition will be a factor if something is attempted here).I think maintaining a single corridor across the entire city is crucial to the feasibility of the line. I don't see a reason to break it in the Bridle Path neighbourhood because of property values or whatever else. This isn't the Spadina Expressway where we would be splitting a community in twain, and this isn't opening up the area to more private vehicles either.
The question then becomes two-fold: (a) How are commute patterns enhanced by a connection through Bridle Path that aren't already resolved by the parallel Eglinton Crosstown route, and (b) what destinations are reached by this connection?
On the former point, I would imagine that most west-bound commuters will alight at Don Mills to head downtown. So I imagine that the number of passengers who would continue their journey crosstown would be fairly small between Don Mills and Lawrence Park. Of those remainder passengers, how many would be better convenienced by a direct connection to the Eglinton Crosstown and to Yonge-Eglinton?
On the latter point, your alignment stops at Glendon Campus, but misses Sunnybrook Hospital which is the main trip generator in the area. The Bayview bus actually stops there for 5 minutes during it's journey due to its importance. For servicing the area, that is why I suggested the western half terminating there.
Finally, there are actually benefits to having shorter routes. Run times can be more reliable throughout the corridor than compared to a longer route. I wouldn't say there is a "correct" answer here, just various pros and cons that should be weighed against each other.