Parhaps I am the only person to have mastered shapeshift since they let you learn shapeshift skill without mastering it, but heres the log.

<100%hp 28%m 100%mv> You flicker and blur into the shape of a giant pig.
You have perfected shapeshift!
You feel a sudden rush of insight into shapeshifting.

You concentrate a moment and return to your normal shape.

<100%hp 17%m 100%mv> c shape scor
You flicker and blur into the shape of a giant pig.
You feel a sudden rush of insight into shapeshifting.

And there is no diffrence that I notice of course. I am below level 33 so I can not learn the skill yet also, I might add.

Thanks