exapt the point of more width (16), there is no reason anymore to use the heavy board shield at all...
i like the Long Pavise Shield, but on horse its just overpowerd in my opinion, just reduce the armour and hit points a bit and it will be still the best cav shield but not that good on foot
if i look on that pic i have to say that it is as well a bit to height (15-20 points) compared to what was the heavy board shield was meant for