Thanks guys!

I'll certainly keep you posted.
I've been at this, bit by bit since February. I only get the cameras a few days a month, and what hasn't helped is the atrocious weather lately in the UK - like one town got a month's rain in a day last week! Floods in June..?

And of course there's figuring out a workflow. The way I'm going to this is keep the + and - together and not sperate them, edit then grade it as per normal (once for + and again for -), and only then seperate out the two streams and tone-map them in one go, seperating out bits that need different tone-map settings. And the stereo tools in Speedgrade CS6 should be a great help.
So easy to get disorganised with a project like this and be driven completely mad!