Gavin - I'm sure you will get a lot of response to this post, and I for one cannot give you any help from personal experience with smoke systems. I do have an interest in them for my next project, and perhaps the Yak I'm about to maiden. While you're waiting for others with experience to respond, here's some information I've found to be quiet interesting on the subject, and you may as well.

http://www.rcuniverse.com/magazine/a...article_id=455
and
http://www.rcdon.com/html/the_ultimate_project.html

And remember, "Experience is a hard teacher. She always gives the test first, and the lesson sometime later!"

Phillip