I made a universal component (modal) that can be used as inline component
<modal :entity="some">
or via service
this.$modal.open({propsData: {...}, component: ModalForm})
it works fine, but warns about invalid props, because it runs in compileProps step, and propsData will be used later in makePropsLinkFn step (compile-props.js).
I think propsData should also be a source of validation along with element attributes

version 1.0.26 jsFilddle (see console)
version 2.0.0-alpha.8 does not have this problem