I just replaced the 3-step on our 5th wheel toyhauler with the Quadrastep 4-step. It puts the first step closer to the door, and the other steps are closer together and puts the last step a little closer to the ground.
It does make a noticeable difference. Peggy thought it was pretty much not necessary until I actually installed it. Then she thought it was wonderful as it makes climbing in and out much easier for her.
Be advised that you may need to do some work to the mounting frame to make it work since it has a rod that sticks out the side for one of the steps. It moves in an arc and will foul the mounting frame on some units. I had to trim the heck out of my mounting frame to make it work. Worth it though all in all.