MickyD... one thing to remember is that Perfect Space is a "read ahead" effect. This means that it may add some latency if you use it during tracking. It is better to use one of Cakewalk's reverbs and swap out for Perfect Space in the mixing stage.
+1 for Scott's book. If you need help with Perfect Space I'm betting there is a lot of other stuff Scott's book will help you with.... some you might not even know about until you read through it. As I've said before, SONAR's help files are great if you know what you're looking for. When I read through Scott's book, I found things I didn't even know existed.