I've had an HGU56 for about 4 yrs now and am very happy with it. Replaced an old heavy SPH4. I needed as much headroom as possible (I'm tall). I specifically tried on compared the CGF with the 56 side by side & in a headroom limited 206 and the 56 was more compact on top and gave about 1" more headroom - also I like the covered dual visor, vs. the exposed variety or the one with a removable cover, also I found it more comfortable and it is relatively light. I upgraded the liner and earcups with Oregon Aero ones.
It looks quite big (wide) when on, but the top is flat and works well with the Astar long-line window. One negative is if you are flying a longline with the door off and stick your head out when in cruise, the width does catch the wind and will tug your head pretty good - you learn not to stick your head out to far at any real speed. If you are in very dusty conditions I found you have to clean the tracks that the visors run on occasionally (when they become sticky), but other wise, not problems.
I first went for a Large, but had to exchange for a Medium - my hat size is 71/4".