Hi Michael,
"Socially valuable" being defined as work is going to butt heads against the disabled people's movement. The concept instantly devalues the impaired body which may be incapable of producing in the sense you speak of.
While many disabled workers are denied the opportunity to work either due to discrimination of not getting an accommodation on the job, it still remains that there are those who will not be "productive" in the sense of making products. Now, these people are marginalized, cast off as useless under capitalism.
The right to be different may include a right not to produce anything and still remain a valuable part of society.
How does Parecon deal with this matter?
Marta Russell