I only have the one ball that I bought from NERD and I still prescent when feeding. I can get him to eat without prescenting but I usually need to make the rat (FT) do the zombie dance for a few minutes to get a strike. When I thaw the rat out on top of his enclosure the entire day of feeding I barely get the doors of his cage open before he's locked on the rat.

In short I guess what i'm saying is that I get a much stronger feeding responce when I prescent. It's kind of like me on Thanksgiving smelling the turkey cooking all day, by the time it's time to eat my stomach's in knots.