Love the idea. Only problem I can think of would be animation based. Phase Walk is literally a 'teleport straight from A to B' whereas the whole jetpack thing would have to show us jumping backwards/forwards with the jetpack. If there's some form of object in the way, it could be a little tricky to animate.
I've been thinking about the animation as well. As you say, if there is an object in the way it could be tricky to animate. I think it could still be very usefull if you stay in a straight line from the set location.