I will sign back in because I have to say congratulations to Uli - it is a huge impressive project and sounds very good! I hope you can get to use a full extended string library - any one of them alone would allow you a much easier time with the articulation selection and you would not have to work so hard trying to make things expressive.
As I stated previously, the VSL strings sound great out of the box, and when handled by someone with your musical taste and expertise, they will create a spectacular performance. It already sounds excellent in many sections.
This looks like something you could market to singers who want more than a piano to rehearse to. A rather specialized market but I can see it being valuable that way. Also of course, you could also do your own special rendtion with these accompaniments if you got a singer to record - that would be fantastic to do the entire cycles.