Mike, good post, and you've reflected a frustration with Sibelius that others (including me) have felt.
Setting up soundsets in Sibelius is problematic at the best of times (at least for me) and i've got more than one unfinished as a result of sheer frustration with the process.
(Nowadays i use Sibelius for score only, playing back with a small orchestral soundfont i built to get a general idea, and use Logic to build up a more decent 'playback.')
I don't know how well the VI will connect with Sibelius, but i don't think this is a problem with VSL, rather the limited capability of modern Notation editors in general to playback from large complex libraries, and recognise notated articulation. It would seem that developers are roaring ahead in the progress race, and software, especially notation software, still has some catching up to do. (program changes and manual cresc plugins. Ptooey.)It would be rather clever of Sibelius, for example, if they added a column in the Dictionary for assignable keyswitches, then one could automate the process, and enjoy the bliss of just writing articulative directions, and not have to do anything else. However, others far smarter than I, like the esteemed and knowledgable DG, may have a better idea how to put this together.
It may well be, frankly speaking, that marrying VSL's VI to Sibelius specifically may be somewhat of a challenge. The dictionary is useful in Sibelius, as I, even with my modest computer skills have discovered, but there's still a lack of usable input interface that gels easily with modern sample libraries.
Maybe it's worth a try, and getting back here with your progress, so one of the smarter tools in the forum box can give you a better idea. I for one would be interested in how you get on.
My last, and somewhat cheeky question is, how long did it take you to setup and fine tune Giga until you were happy with it?
Regards,
Alex.