I've had the idea for a long time and just been playing since I made the post. However, its very hard to put my idea into practice as the way keying works in QS doesn't suit the way I want to work and makes getting my effect under control very difficult.
I'll have to speak to Bill about this for Beyond going forwards and see what he thinks of my way of working. My main problem is regarding percentages (if you've tried keying you'll know what I'm on about). However, I have other ideas that I'm not going to post publically for sensitivity reasons. In the mean time, this may have to be abandoned as a project as its going to be near impossible to achieve, using the methods I have available at the moment. However, as I've said before, horses for courses. If QS did everything then no-one would want Beyond.