Question on Choir Dress from a NLM Reader

A reader wrote in to ask the following question. I wanted to open it up to the NLM readership, particularly the parish priests out there reading the blog, or the choir directors, to see your thoughts. That being said, it's open to all, not just priests and choir directors (but I figure their expertise and experience would be particularly valuable.)

I'd ask that people avoid throwing out simple personal opinion and try to ground their responses in church documents, present liturgical law as pertains to the modern Roman rite, etc.

The question is as follows:

"What arguments (practical and theological) have been offered for and against placing the choir in robes?"

(I believe there may be some reference to this in the GIRM, but I cannot recall off the top of my head. I know this comes up as pertains to readers, EMHC's, etc.)

Please post a comment on this if you think you can help answer this question.