After much trouble and strife (with many thanks for the patience and expert advice of Andi) I have completed a performance of a 21 minute orchestral/chorus score. It is the 2nd movement of Kaikhosru Sorabji's 'Jami' Symphony. Scored for a double size symphony orchestra and (very briefly) a double chorus with organ, piano, celeste, 2 octave tuned gongs, very chromatic timpani played by four players (looks a bit like a bass xylophone part in places).
You can listen to it here and if you feel so inclined you can read a bit more about it here.
It uses 71 VIs for which I used the full DVD sound sets. I had 7 VEPro instances and used MIR Pro with the Vienna Konzerthaus stage mic in 15th row. It took up just short of 21GBs of my 24GBs of RAM and at it's loudest and most complex was pushing my intel i7 extremem quad core processor to just under 80 degrees. I think the resulting sound is fantastic (and a real testament to Sibelius/VSL). I'm sure there is much I could do to improve the sound thru 'mixing and post pro' but that is the area I am least experienced in.
Any constructive comments as to how to improve the sound would be welcomed.
This is the short 2nd movement. The entire four movements come in at about 4.5 hours. The other movements will require probably about 100 VIs and about 36GBs of RAM so is currently beyond my system capabilities (and probably beyond my sanity). Perhaps when I've upgraded to some SSD drives it may be possible.