Imagine making a Deathmatch where you could perfectly adjust in real time how a grenade bounces off a wall, by adjusting the distance of the wall, then alt tabbing to live edit to test again. No need to start/stop game, and all mechanics are there and running.
Having the ability to move props while the game has started will immensely speed up iteration time, even when compared to UGC editors, because all of them require the game to stop for iterations to be made, but that’s not necessary when you have two versions of the game active (UEFN and live edit). So editing things in UEFN would update live edit in real time while the game has started, and it would allow for incredibly quick updates and development.
This feature could be the turning point on the areas where the editor lacks agility due to iteration times. Then if this proves doable and works, devices can follow, then verse.