Automatic Litterbox Central

For those of you who have tried both the Forever Tray and the homemade coroplast tray, how do they compare? I am going to finally invest in a ScoopFree (considered Smart Scoop, but my nervous kitty is doing really well with the crystal litter and I am afraid to switch to something else). Of course I don't want to replace the cartridge, so I want a reusable. I usually have coroplast around the house for other projects, so I am wondering: how does the homemade coroplast tray compare to buying a Forever Tray or a Permascoop? Thoughts?

Forever tray, hands down. No possibility of leakage.