A 'Teleport' spell with non-Momentary Duration?

Oh, but I don't want to have that spell. In fact I'd rather it didn't come up in play at all!
But sadly the teleportation-Mercere's player asked: "What happens if I do this?". The current SG at that time answered "You'll give me a headache is what happens!"
But then we began talking, and my idea seemed the logical choice. And it sounded like good discussion material for the forum.