Hi ArenMook,
Sorry for digging up this one, but after searching the forums the OP's second example is exactly what I'm currently facing (using NGUI v3.6.

1. Setup a UIPlay Tween with the trigger condition: On Hover True, Tween group 0. Tween Scale From 1.00 To 1.75 on all values, Tween group 0.
2. Setup a UIPlay Tween with the trigger condition: On Hover False, Tween group 1. Tween Scale From 1.75 to 1.00 on all values, Tween group 1.
First time I hover over it works fine, hover out perfect as well. But after that it jumps straight away in the scale I've defined.
Would the solution you mentioned also help avoid this? If so in which script should I adjust this?
Thanks in advance!