To me the slope graph looks really messy and I think I'd have trouble looking at it, especially across eight time series.
I am not an expert in graph design, so this may also be a no-go, but have you considered four colors with three types of plot type?
Though, I think there is an even better approach. I know you say that 4 colors is a no-go, I'm about to ignore that. It is probably canonically true... but you are describing fruits. These have canonical colors as well as shapes associated with them. If you use those colors and shapes I think it would be hard to go wrong.
Using colors alone there might be some confusion, e.g. green apple vs honeydew, red apple vs watermelon, etc. But using colors poses an additional problem, color blind individuals. You can test for the extent to which this would be a problem by creating an image of your different colors and looking here: http://www.vischeck.com/vischeck/. Protanopia and Deuteranopia, forms of red-green color blindness, are by far the most common (occurring almost always in males). Even so, color blindness is a misnomer and if you select your pallet carefully the differences in shades may be sufficient.
In conjunction with a color approach, you want to use fruit shaped points. These are unlikely to be a default in a plotting program and you may have to spend some time in photoshop to make it look right. Even if you can't take that time, differing geometric plot points AND color should make things reasonable.
Moreover, you could use the approach I suggest with a slope graph.
As a side note, if you have a technically/mathematically astute audience, a Y-axis in log odds might mean more to them that percentages alone.