Well, it does make sense that a faster creature will be able to outrun a slower creature. I think you have your equation backwards, btw, shouldn't it be 2M+5? On the other hand, I think there were rules about flying at 1ft (or similar height) above ground and that it does not mean you could just direction instantly (maybe Draconomicon has more on it). In any case, as long as the chaser's movement is high enough, he can pick one direction and try to cut off the victim. Remember that the victim must pre-choose a location and the condition (not plural) upon which to move. There might be a way to guess where he flees and cut him off.
Another, interesting case occurred in Arborea. As long as creatures get out of the area before the Thunderbird's initiative, they can ignore the sandstorm (control winds) with relative impunity. In other words, the Neutral will never enter the arena on the Thunderbird's initiative (obviously), so they'll never be affected by the hurricane force winds. They move and fly up and there good to go with never a saving throw needed versus the wind.
