I just installed GigaStudio Orchestra 3.1 and the Sonic Implants Complete Symphonic Collection. I was so impressed with these samples that I got a Win PC to hook up to my Mac to run GigaStudio. I just posted something to the Sonic Implants forum elsewhere on Northern Sound, and you can read my posts there if you're interested.
I have been tinkering around with GigaPulse and have taken a short piece that I scored using SI instruments and tried it with no plug-ins (no EQ, reverb, etc.) and then applied four different convolution reverbs using GigaPulse. If you have a minute, check them out and let me know what you think. They are labeled and numbered if you have any comments.