I have been using the flat type fender for the past 20 years or so on past and present fleet of yachts. I will never go back to the round style.
Goods
they store well.
dont mark the hull.
Can sit on them.
dont deflate.
they don't compress as much.
bads
they blow around abit when it's windy.
they don't roll when you slide along the dock.
a good tip I learnt is to write your mobile number on them!