Based on data from 1999-2002, a number 3 hitter will hit with 2 outs 37% of time while a number 5 hitter will do that 33% of the time. A number 3 hitter will hit with runners on base 48% of the time, as will a number 5 hitter, but the number 5 hitter will have 3.1 runners on per game vs, 3.00 for number 4 hitters. (Source - Tango, Lichtman, and Dolphin, The Book: Playing the Percentages in Baseball, p.122) At any rate, the order is not hugely important, though it can make a small difference.