The 3-2 zone doesn't affect the RB rating so if you want to counter outside offense it is a good choice. The 1-3-1 zone should be used with caution if your playing against an onside offense or a team with good RB.
What you mean 3-2 doesn't affect rebounding? If that's the case, I should try it out more often :)
Would you mind giving us more info about your 3-2 zone experiences?