Yeah, well the official thing is that you must have two HEXbs if you are doing red/green and one-two HEXas. One is enough as far as getting your calcium is concerned, but there was always the option to have more than one if you wanted milk and cheese (which I always do!).
As far as HEXbs are concerned, this was one of my first questions in group - what about fibre? The consultant didn't really have an answer, but said that it wouldn't have been released if it wasn't safe so not to worry about it. I'm not convinced, how can you say one day that you need two HEXbs to get enough fibre and then all of a sudden change it?
Although, to be honest, I was always a bit suspect about the HEXbs providing fibre. Fruit and veg has the most fibre, far more than a HiFi bar for example!