I would LOVE some other examples of using friendly leap in boss encounters (trash should not be causing issues). I'm always worried about pulling the boss out of position with it.
It's a general threat reducer and dmg mitigation buff, so that's nice in general. Specific boss mechanics where it can be put to use:
Returning Toth to position.
Instantly rotating Stormcaller's turret during Double Destruction.
Getting puzzle-solving tank into Vorgath fight with maximum speed.
Reducing damage Warstrider bomber during Kephess fight.
Moving quickly across lava during Gharj encounter.
Moving quickly back to outer ring during Soa encounter.
Getting out of range of 'Doom' in 2nd Boss of TFB.
There are probably others - it's a versatile ability that definitely gets under-used in PvE.