The only thing about steps is if you have heavy-weight birds, like Pekins, I worry about their legs. At least I always worried about my girls when they would try to get up my steps - I always tried to grab them and set them on the ground so they didn't hurt themselves. Light weight birds might...
Covering a wooden ramp with astroturf or indoor/outdoor carpet is nice because it's soft on their feet and not slippery. You can hose it off when it gets dirty.
Ducks will never be able to do a ramp that has slats like that - you need a solid surface that is easy to grip, that also is a very shallow climb if you have the larger breed ducks. They need a step to get out as well - you can use concrete blocks on the inside.