I have covered the ramp with Fleece, & the incline is a bit slippery, so I suggest a mat of some sort for the floor. I think because the side is "open" to be seen inside the cage, they really do not potty in the ramp.
We re-homed babies, so I added a coro lip all around the perimeter of each floor. My 2 month olds can still squeeze through the grid squares.
I took out the "canopy bed" in the loft and added 2 snuggle sacks that we use for lap time as well.
My girls LOVE running laps in all directions and patterns! Happy Gpiggies need long lap routes!