Thanks k-dog. Not worried about how it will all look, but I reckon shimano brake-shifters, at least tiagra with the paddles would work well on the sides of butterfly bars. Also, when you think about it, when riding on the flats, it wouldn't be too much of a finger stretch to reach them either.
Not as much of a stretch from riding on the flats on drops to reach the gears on the hoods, which is probably more destabilising anyhow.
To set the whole thing up would probably be the same as setting up bar top brakes on a cross type bike