If I understand you correctly, nothing in this piece is VSL?
The reason I went with VSL, when I was auditioning sample libraries, was not just because of the fantastic sound but because VSL offered more flexibility with the VE engine. Although I think Eastwest puts out an impressive product, I own the symphonic choirs myself, I thought that VSL just gave the user more options with regard to things like Velocity Crossfade, Attack, Release Keyswitching, articulations, Repititions speed control, etc. To me, it seemed that Eastwest was designed for the "big Hollywood sound" which is fine if that's all you want to do, but I just wanted more flexibility.
I'm not sure if VSL will make your pieces sound any better but I think, once you get used to working with the interface, you could compose different pieces that don't sound so homogenous. Others on this forum would tend to disagree, stating that VSL is far better sounding than anything else on the market and is the answer to all of your composing needs. Although I respect their opinions, I'm not completely convinced of that as of yet. However, VSL is the answer to all of my composing needs at this time.
I don't know if that answers your question but good luck to you and a nice piece anyway.