One theory regarding Chain suck is that it will occur with alloy chainrings. I had read several articles that mentioned that chain suck was rarely an occurance with Shimano LX groupsets and lower. The difference is LX used steel for its 22 toothed inside chainring.

Is the theory valid? From my own personal experience, I've exchanged the inside chainring of my crankset to the 22 tooth chainring from Shimano's LX groupset. Chainsuck has been eliminated completely.