Live track would only work if the BlackBerry hardware was capable of connecting to the Garmin watch. Since BlackBerry has no devices supporting BLE (Bluetooth Low Energy) this won't be possible. At all.
Untrue. The Q10 and Z10 use BLE.
http://ca.blackberry.com/smartphones/blackberry-q10/specifications.html
In Canada, about 20% of smartphone users have a blackberry. That's a lot of potential customers who, as it stands now, would not get the same features as apple users.