I know you were saying it wasn't worth it, but because it would stack with magical effects the way a certain other spell wouldn't, I've removed that line. Instead I added other bestow curse-like effects.
I also removed the Save or Die aspect of the teleportation and put in the wish-like language that I was assuming from a metagame standpoint.
The teleportation also has average, dimensionally shrinking, error factors accounted for. The maths:
planeshift's 3-d 5*d% minimum is 5*1=5 miles
Then a studied teleport within those 5 miles has a 95% chance to be on target, so we'll chop off 95% of that error: 5*.05=1320' (We ignore the off-target distance since it could put you right back on target via 100% distance in the correct direction)
We assume that the teleport above drops the error from a 3-d sphere to a 2-d circle. We apply the same factor of 20 again to the drop from a 2-d circle to a 1-d line to get an averaged version of greater teleport: 1320/20= 66 feet.'
Since demiplanes are defined as being small, we cut the error factor down by an integer.