Hi Marco,
My workflow starts by composing a piece as a piano arrangement - sitting at my piano and using blank staff paper and a pencil (not very high tech). Once I have a suitable piano arrangement with melody and harmony, I will produce a short score in Sibelius, whereby I assign the various intruments (strings, woodwinds, brass and percussion). I use the Sibelius/VSL presets so that I can hear how my voicings and instrumentations are working out within the compsoition. I spend a lot of time on this step - this is the real compositional phase for me.
Once the piece is fully written out and arranged in Sibelius, I export it as a midi file in Cubase, start up VE Pro and start assaigning VI Pro instruments for each midi track. At this point, it's just a matter of making a realistic mockup. This is where I will use keyswitches along with manual edits in velocity and C11 expression. While I've tried using the velocity crossfade function, I feel I get a better sound by adjusting velocity and C11 information separately. It helps if you have an intimate knowledge of instrumentation as you'll know the exact sound you want. This helps in choosing the various articulations. I've found that for realistic mockups, you really need to use a wide variety of articulations. Obviosuly Jay Bacal feels the same way!
Another way to increase realism is to play in the midi parts individually in order to have more realistic variations in tempo. When I do this, I just choose a generic articulation and then once the part is played in, I do a lot of editing of velocity, C11 and make articulation changes.
All the mockups at my site www.corteswearingen.com use VSL sound libraries exclusively. I think a lot of people that don't care for the VSL libraries are teh ones that haven't taken the time to really understand and use them. There is no doubt that the VSL system (VE Pro & VI Pro) has a high learning curve.
Corte