Transient fields are not rendered. A configuration like the following only renders the model property acme:modelProperty but not the transient property acme:transientProperty.
In Alfresco 4.2f it was possible to use transient forms like this. In Alfresco 5.0d only the acme:modelProperty is rendered.
acme:transientProperty is rendered using the configured control. It must be possible to render such a property inside a set.
I rate this a Critical issue because it breaks valid Share customization in a major way.