Quick initial comments:
Without poi'a, the purest way to say "you dance beautifully" would be "da ge nu dansu gi melbi". Likewise "(na) da ge cumki gi nu do sipna", without soi'a. But poi'a and soi'a are convenient, and noi'a affords something genuinely new. Indeed, poi'a allows us to neatly say "I expected it to rain and it did rain" and "I expected it to rain but it didn't" as "(na) carvi poi'a I expect ke'a".
I think "poi'o'a xagji" is not quite right or necessary as described. "x leave willingly" is "x cliva poi'a x willing to ke'a", "x leaves and is willing to do so". So "x leave angrily" is "x cliva poi'a ke'a has the characteristics of lo nu x angry". Why define poi'o'a so narrowly as "poi'a ke'a has the characteristics of lo nu vo'a", when it would suffice to use poi'a plus a version of vo'a that is somehow defined so as to always point to the right x1? Or otherwise, is there a way to extend poi'o'a to cover "willingly"?
Of the syntax options, Option 2 looks best for the actual accomplished user, while Option 1 is best for those who would rather pare away some of Lojban grammar's overexuberant complexity.
--And.