Appreciate the reply.
A new tween each time should be fine - as its using left/top and is absolute positioned, only the start should be different (the end should be a top/left value that is absolute)
Unfortunately, there is still some funkyness with percentages.
Take this for example:
http://jsfiddle.net/4GeQe/12/
It only obeys the unit measurement, but not the percentage measurement. Until the end, when it snaps into position.