My personal opinions on this subject:

1) As long as the author gives a justification for how the curse 
behaves, and it's well reasoned out, either works for me.

2) I, personally, will use either, depending on what I'm trying to 
accomplish with my fanfic. 

3) I have always tended to hold the opinion that the curses are 
"shiftable". I've observed the curses doing some strange things--
growing minotaurs, expanding busts....but the most evident curse 
which shifts is Ryouga's curse.

Whether an intentional thing, or a design flaw, P-chan's size changes 
constantly. Most of the time he tends to be very small and cuddly. 
Other times, he's much larger, more reminiscent of a potbellied pig. 
This mostly, I believe, happens in the anime, but it does happen. I 
prefer to think of it as an effect of the curse rather than a 
continuity or animation error.

And as stated numerous times...there are no set "laws" for Jyusenkyou 
curses, other than if you fall in a spring, you get cursed, and cold 
and hot water affect your transformation. Anything else is completely 
in the purview of the authors.

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The Eternal Lost Lurker
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