In reply to yorkshireman:
OK, after some Googling around I found the workaround. Simply ensure you set the camera to GoPro Hero (regardless of what the source camera was) and click 'Advanced Smoothing' rather than 'Standard' and it renders without crashing.
Here's the quick test I did - - a bit Endor speederbike chase in places
Will need to experiment but I don't think the result is too bad considering the very aggressive shake on the source video (I was running, just carrying the camera in my hand).