myth 1.1.1 vs cssnext 0.3.1

_input.css

a { font-size: calc(calc(calc(1rem * 0.75) * 1.5) - 1px); }

a { color: color(rebeccapurple a(-10%)); }

a { color: hwb(0, 10%, 20%); }

a { color: color(color(red a(+10%)));}

a { color: color(color(rebeccapurple a(-10%)) a(-10%)); }

:root { --not-a-color: 4px }
a { color: var(--not-a-color, green) }

/*
@todo before cssnext v1.0
https://github.com/postcss/postcss-import/issues/2
https://github.com/postcss/postcss-custom-properties/issues/4
*/

cssnext.css

/* http://putaindecode.github.io/cssnext-playground/ */

/* better, & works today in most browsers */
a { font-size: calc(1.125rem - 1px); }

/* resolved */
a { color: rgba(102, 51, 153, 0.9); }

/* resolved */
a { color: rgb(204, 26, 26); }

/* resolved */
a { color: rgba(102, 51, 153, 0.81); }

/* fallback ok! */
a { color: green; color: 4px }

myth.css

/* http://jonathankingston.github.io/mythhub/ */

/* unresolved */
a {
  font-size: calc(calc(calc(1rem * 0.75) * 1.5) - 1px);
}

/* unresolved */
a {
  color: color(rebeccapurple a(-10%));
}

/* unresolved */
a {
  color: hwb(0, 10%, 20%);
}

 /* wat ? */
a {
  color: rgb(0, 0, 0);
}

/* syntax error for a { color: color(color(rebeccapurple a(-10%)) a(-10%)); } */


/* not a valid color, no fallback :/ */
a {
  color: 4px;
}

So there is a clear win for cssnext?