[rules-users] split constraint same as LHS of rule

We have recently started using flow along with rules. We noticed that for our split constraints, those constraints often matched the LHS of our rules. We took the approach of removing the constraint from the rule, under the premise that we would only need to have the constraint one place, and not duplicating the constraint would be helpful if we ever needed to change the constraint. We are using POJO for data, with a "decision" object holding the input data. The LHS of the rule now just looks to see that there is a decision object. This works just fine. My question is whether there is some reason why we ought to keep the constraint in both places--is there any known down side to having the constraint be just within flow? -- Kathy