Hi,
Both companies kind of disappeared. But build plans are still travelling on the Internet.
I can't answer your question, and I think you should try to get hold of both build plans and make your own opinion. To me, it looks however that Saturn design is much more popular than the Vodou one, but people who built MX5 based Roadster will be able to give you a better answer than me (Sierra based Roadster).
But, there is a thread on LCB about that. There is lot of blah-blah, but also very good and useful information I think, it can be a good start:
http://www.locostbuilders.co.uk/view...php?tid=164784
hope this can help