I say it would work based on the example I posted (which works). It produces the exact same plan and answer (except for the leading comma) as what Chris Posted which I believe is guaranteed to work. I need to read the article a little more (as well as this one[/url]) but I think it should work just fine.

The article you posted seems to imply that there is a problem applying expressions to members of the ORDER BY clause; I am not using an ORDER BY since the requirement does not call for it. From the article:

Under Symptoms (emph mine):

You may encounter unexpected results when you apply any operators or expressions to the ORDER BY clause of aggregate concatenation queries.

Under Cause:

The correct behavior for an aggregate concatenation query is undefined...

... When an expression is applied to a member of an ORDER BY clause, that resulting column is not exposed in the SELECT list, resulting in undefined behavior.

Under Work Around: (emph mine)

In order to achieve the expected results from an aggregate concatenation query, apply any Transact-SQL function or expression to the columns in the SELECT list rather than in the ORDER BY clause.

I could be wrong but I don't believe this article applies.