Hi Matt,
I have just finished writing a reply to a post that someone asked me to view, and it is in relation to sibelius 5. I have sib 5 and Vienna Instruments working just great together, and there are also others on the forum who are using it well and succesfully also.
Unfortunately, it is now time for me to hit the sack in Australia at the moment [bedtime here and getting late now!], but I will try and get back to you and be as helpful as I can when I get the chance to post again, which won't be until Thursday night Australian time.
Until then, I would recommend that you try sibelius 5 with the soundsets, and read and re-read the instructions if something is not working. I can say from my experience using Sib 5 and Vienna Instruments that when something is not working, there is always a logical explanation for it, and when using it for the first time, you really must stick close to all instructions in the info provided with the soundsets, and everything should work fine.
Once you get used to following the set pattern of setting up the score etc, it gets easier and easier. I've also found a few ways to make scoring a lot easier when using Vienna Ensemble, and Sibelius 5 together in relation to what instrument in each staff relates to what numbered instrument in each slot of the Ensemble. Anyway, I can get into this later.
best regards,
Steve[:D]