1. Try Blends is one way, --- 2. using the contour tool, press Ctrl+Shift+S, then Ctrl+U, then move to suit. These two methods keep it vector and I would go from dark to lighter colour. You could also try cloning shape, and using if you want a floor shadow, using the Mould Tool and maybe a linear transparencies although these are also rendered the same as shadows as a bitmap. Feathering any object to a nice soft edge is also rendered as a bit map. This is the area that can cause the problems if drawn over something else. Also if you were using arrows from the design galleries some of them are given weird fills and separate lines with many, many control nodes. Don't know about ver. 10 mind you with the smart arrows. Even though I am a mod. I don't want a version that hasn't added anything to help me draw vectors and I feel embarrassed at the situation. The easiest way to solve any of these RGB effects which are rendered as a bitmap is to make a soft group of the object and if you can the background to the object and make "A bitmap Copy" (Ctrl+Shift+C) and that solves the problem when it comes to print. Should say with True Alpha Colours selected from the popup menu.