Ahh, thats cool. Your example has made me realise that my issue is with how tween scale is working and nothing to do with what I thought.
If you change your example so that the Tween is Scale, x=2, y=2, ping pong loop and then run it and click a few times you will see the sprites grow out of control. Thats my issue :)
I just need to turn off the loop and only re-execute the tween after it's finished a cycle (i.e Scale needs to be back to 1 before running again). You, see I need to tween on every tick and they are exploding :) I'm trying to pulsate them but all at different rates based on how old they are (which is my instance variable)
You are a star, thank you so much for taking away the pain :)