Question about iRobot Roomba i7

Hello, I've been thinking about buying the i7158 for a long time. But I'm also still thinking about the 980/981 model. Can't really decide either. Does anyone have any experience with black base plates? I have heard and also read before that black floor plates could be recognised as abyss. It's difficult (return) to decide on a model when you realise that it doesn't work.